JP2007039748A - HEAT RESISTANT Al-BASED ALLOY - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lightweight heat resistant Al-based alloy having excellent heat resistant strength and wear resistance. <P>SOLUTION: The Al-based alloy has a composition consisting of 15 to 35%, in total, of 5 to 15% Zr, 1 to 8% Fe, 1 to 8% Cr, 1 to 8% Mn, 0.5 to 5% Ti, 0.5 to 5% Ni, 0.5 to 5% Si and 0.5 to 5% V and the balance Al with inevitable impurities. The structure of the Al-based alloy consists of, by volume fraction, 35 to 80% intermetallic compound phase and the balance Al matrix. The above intermetallic compound phase contains Al-Zr intermetallic compound phase, and one or more elements among the above Fe, Cr, Mn, Ti, Ni, Si, and V are allowed to enter into solid solution in the Al-Zr intermetallic compound phase and the total of these elements in the state of solid solutions is made to ≥7 mass%. In this way, heat resistant strength and wear resistance can be improved. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is an Al-based alloy that is excellent in wear resistance and rigidity, and has a heat resistance strength (high temperature) of about 300 to 400 ° C. among applications such as engine parts (pistons, connecting rods) of automobiles and aircrafts. It also relates to a heat-resistant Al-based alloy suitable for use in machine parts that are required to be lightweight.

  Various heat-resistant alloys such as Al-Cu alloys (2000-type Al alloys such as 2618) have been developed as conventional melt-cast alloys. However, sufficient heat-resistant strength is achieved at high temperatures exceeding 150 ° C. Could not get. This is because Al—Cu-based alloys ensure strength with fine precipitates obtained by age hardening, and therefore, when the use temperature exceeds 150 ° C., the precipitate phase becomes coarse and the strength is significantly reduced.

  Thus, conventionally, Al-based alloys to which the rapid solidification method is applied have been developed. According to the rapid powder metallurgy method, which is one of the rapid solidification methods, the amount of addition of alloy elements such as Fe, Cr, Mn, Ni, Ti, Zr, etc. can be increased as compared with the melt cast Al alloy. Therefore, an Al alloy containing a large amount of these alloy elements is pulverized by rapid solidification and solidified and molded to obtain an Al-based alloy having excellent heat resistance even at high temperatures exceeding 150 ° C. Yes (see Patent Documents 1 and 2). This is because the alloy element disperses an intermetallic compound with Al that is stable even at a high temperature in the structure, thereby increasing the heat resistance strength.

  Furthermore, a technique for increasing the strength by increasing the fraction of the intermetallic compound by miniaturizing the intermetallic compound has been proposed (see Patent Document 3).

  In addition, alloying elements such as Fe, V, Mo, Zr, and Ti are added by spray forming, which is one of the rapid solidification methods, and the intermetallic compound between these alloying elements and Al is refined to reduce weight. A heat-resistant Al-based alloy has also been developed, and a high-strength Al-based alloy that also has wear resistance has been developed by adding excess Si and refining primary crystal Si (see Patent Document 4). ).

Furthermore, a quasicrystal is formed in a matrix made of a heat-resistant Al-based alloy (see Patent Document 5) made amorphous by adding various alloy elements other than the above, and a supersaturated solid solution added with two or more transition elements. A heat-dispersed Al-based alloy (see Patent Document 6) uniformly dispersed, an impeller obtained by hot extrusion of an Al—Fe-based rapidly solidified Al-based alloy and further hot forging have been proposed (Patent Document 7). reference).
Japanese Patent No. 2911708 (full text) Japanese Patent Publication No. 7-62189 (full text) Japanese Patent Laid-Open No. 5-195130 (full text) JP-A-9-125180 (full text) Japanese Patent Publication No. 6-21326 (full text) Japanese Patent No. 3142659 (full text) Japanese Patent Laid-Open No. 10-26002 (full text)

  According to the quenching powder metallurgy method such as Patent Documents 1 to 7, the heat resistance strength of the Al-based alloy can be increased (the level of 300 MPa at about 300 ° C.) by increasing the addition amount of the alloy element. However, if the amount of alloying elements added is increased too much, the size of intermetallic compounds will be increased, so in structural materials that require wear resistance, chipping will occur from these coarse compounds and the wear resistance will be reduced. Let

  These Al-based alloys are composed of a metal Al matrix and an intermetallic compound phase, and have a dispersion strengthened structure in which a hard intermetallic compound phase is dispersed in a soft metal Al matrix.

  In such a dispersion strengthened structure, the strength of the metal Al matrix is relatively low, so when used in machine parts that require heat resistance and light weight, a hard intermetallic compound phase cannot be retained on the surface. There is also a problem that wear resistance and rigidity are lowered.

  This invention is made | formed in view of this problem, and it aims at providing the heat resistant Al group alloy excellent in heat resistance strength and abrasion resistance.

  In order to achieve this object, the gist of the heat-resistant Al-based alloy having excellent wear resistance and rigidity according to the present invention is, in mass%, Zr: 5-15%, Fe: 1-8%, Cr : 1-8%, Mn: 1-8%, Ti: 0.5-5%, Ni: 0.5-5%, Si: 0.5-5%, V: 0.5-5%, respectively And the total content of these elements is 15 to 35%, and the balance is an Al-based alloy composed of Al and inevitable impurities, and the Al-based alloy structure has a volume fraction of 35 to 80%. The intermetallic compound phase and the balance are composed of a metal Al matrix, and the intermetallic compound phase structure has an Al-Zr-based intermetallic compound phase, and the Al-Zr-based intermetallic compound phase includes the above-described intermetallic compound phase. One or more of Fe, Cr, Mn, Ti, Ni, Si, and V are in solid solution, and the total of these dissolved elements is And it is mass% or more.

  In the present invention, each intermetallic compound particle is referred to as an intermetallic compound, and an aggregate (continuous body) in which a plurality of these individual intermetallic compound particles are adjacent to each other is referred to as an intermetallic compound phase. In addition, the Al—Zr-based intermetallic compound referred to in the present invention means that the content of Zr is excluded except for Al among constituent elements (analytical elements) of an intermetallic compound containing Zr by an analysis method described later. It refers to the intermetallic compound showing the highest value.

  The Al-based alloy according to the present invention is composed of a metallic Al matrix (a matrix composed of metallic Al, hereinafter simply referred to as Al matrix or Al matrix) and a large amount of the intermetallic compound phase. In addition, a dispersion strengthened structure in which hard intermetallic compound phases are dispersed. In such a dispersion strengthened structure, as described above, since the strength of the Al matrix is relatively low, a hard intermetallic compound phase is formed on the surface when used in machine parts that require heat resistance and light weight. There is a problem that it cannot be held and wear resistance and rigidity are lowered.

  Furthermore, as in the present invention, when the amount of the alloy element added is increased and the intermetallic compound phase is increased, the wear resistance of the Al-based alloy becomes more limited in the strength of the Al matrix. In other words, when used in the heat-resistant machine parts, there is a problem that the strength of the Al matrix that can hold the hard intermetallic compound phase on the surface is more required.

  In such an Al-based alloy, the present inventors, in the case of an Al-based alloy that essentially contains Zr, which is widely used as an alloy element for improving heat resistance, has a combination of heat resistance and wear resistance depending on the combination of the alloy elements. And found that the difference is greatly different.

  That is, in the case of an Al-based alloy containing Zr as an essential component, not only Zr alone, but also a combination of Zr-Fe-V system or Zr-Fe-V-Si system in which an alloy element is further added to Zr, There is little improvement effect with wear resistance. On the other hand, when the number of alloy elements is further increased and seven specific alloy elements such as Fe, Cr, Mn, Ti, Ni, Si, and V are contained together with Zr, it is practical only for the first time. The improvement effect of the heat resistance strength and the wear resistance in the sense was seen.

  Seven specific alloy elements such as Fe, Cr, Mn, Ti, Ni, Si, and V are stable intermetallic compounds of L12 type Al3 Zr together with Zr when an Al-based alloy is produced by a rapid solidification method. Form. In addition, when the Al-based alloy is produced by a rapid solidification method, one or more of these specific alloy elements are further dissolved in the Al-Zr intermetallic compound phase.

  As a result, the Al-based alloy of the present invention has higher heat resistance than when the Zr stable intermetallic compound is not formed or when the element does not further dissolve in the Zr stable intermetallic phase. Abrasion resistance can be remarkably improved.

(Al-based alloy composition)
The chemical component composition (unit: mass%) of the Al-based alloy of the present invention will be described below including the reasons for limiting each element.

  As described above, the basic chemical composition of the Al-based alloy of the present invention is, in mass%, Zr: 5 to 15%, Fe: 1 to 8%, Cr: 1 to 8%, Mn: 1 to 8%. Ti: 0.5-5%, Ni: 0.5-5%, Si: 0.5-5%, V: 0.5-5%, respectively, and the total content of these elements Is 15 to 35%, and the balance is made of Al and inevitable impurities.

  In the Al-based alloy of the present invention, in addition to these basic chemical component compositions, one or two of Cu: 0.5-5%, Mg: 0.5-3%, and / or One or two or more of Nd: 0.2 to 2%, Sc: 0.1 to 2%, and Ag: 0.1 to 2% may be selectively included.

(Zr)
Zr is, Fe, Cr, Mn, Ti , Ni, Si, V, along with certain alloying elements seven such, when prepared by the Al-based alloy rapid solidification, Zr with such L ₁₂ type Al ₃ Zr Forms stable intermetallic compounds. And it also dissolves in the Al matrix to improve the heat resistance and wear resistance. In order to exert these effects, the Zr content is set to 5 to 15%. If it is less than the lower limit of 5%, a sufficient amount (number) of intermetallic compounds and a solid solution amount in the Al matrix cannot be obtained, and the characteristics such as the heat resistance strength and wear resistance cannot be improved. On the other hand, if the upper limit of 15% is exceeded, a coarse compound is formed and, on the contrary, these properties are impaired. Therefore, the range of the Zr content is 5 to 15%.

(Fe)
Fe forms a stable intermetallic compound such as L ₁₂ type Al ₃ Zr together with Zr and six other specific alloy elements. And it dissolves also in this intermetallic compound and Al matrix, and improves heat-resistant strength and abrasion resistance. If the amount is less than the lower limit of 1%, a sufficient amount (number) of intermetallic compounds or a solid solution amount in an intermetallic compound or an Al matrix cannot be obtained, and the characteristics such as heat resistance and wear resistance cannot be improved. On the other hand, if the upper limit of 8% is exceeded, a coarse compound is formed and, on the contrary, these properties are inhibited. Therefore, the range of Fe content is 1 to 8%.

(Cr)
Cr forms a stable intermetallic compound such as L ₁₂ type Al ₃ Zr together with Zr and six other specific alloy elements. And it dissolves also in this intermetallic compound and Al matrix, and improves heat-resistant strength and abrasion resistance. If the amount is less than the lower limit of 1%, a sufficient amount (number) of intermetallic compounds or a solid solution amount in an intermetallic compound or an Al matrix cannot be obtained, and the characteristics such as heat resistance and wear resistance cannot be improved. On the other hand, if the upper limit of 8% is exceeded, a coarse compound is formed and, on the contrary, these properties are inhibited. Therefore, the range of Cr content shall be 1-8%.

(Mn)
Mn forms a stable intermetallic compound such as L ₁₂ type Al ₃ Zr together with Zr and six other specific alloy elements. And it dissolves also in this intermetallic compound and Al matrix, and improves heat-resistant strength and abrasion resistance. If the amount is less than the lower limit of 1%, a sufficient amount (number) of intermetallic compounds or a solid solution amount in an intermetallic compound or an Al matrix cannot be obtained, and the characteristics such as heat resistance and wear resistance cannot be improved. On the other hand, if the upper limit of 8% is exceeded, a coarse compound is formed and, on the contrary, these properties are inhibited. Therefore, the range of Mn content is 1 to 8%.

(Ti)
Ti forms a stable intermetallic compound such as L ₁₂ type Al ₃ Zr together with Zr and six other specific alloy elements. And it dissolves also in this intermetallic compound and Al matrix, and improves heat-resistant strength and abrasion resistance. If the amount is less than the lower limit of 0.5%, a sufficient amount (number) of intermetallic compounds or solid solution amounts in the intermetallic compound or Al matrix cannot be obtained, and the above characteristics such as heat resistance and wear resistance are improved. Can not. On the other hand, if the upper limit of 5% is exceeded, a coarse compound is formed and, on the contrary, these properties are inhibited. Therefore, the range of Ti content is 0.5 to 5%.

(Ni)
Ni forms a stable intermetallic compound such as L ₁₂ type Al ₃ Zr together with Zr and six other specific alloy elements. And it dissolves also in this intermetallic compound and Al matrix, and improves heat-resistant strength and abrasion resistance. If the amount is less than the lower limit of 0.5%, a sufficient amount (number) of intermetallic compounds or solid solution amounts in the intermetallic compound or Al matrix cannot be obtained, and the above characteristics such as heat resistance and wear resistance are improved. Can not. On the other hand, if the upper limit of 5% is exceeded, a coarse compound is formed and, on the contrary, these properties are inhibited. Therefore, the range of Ni content is 0.5 to 5%.

(Si)
Si forms a stable intermetallic compound such as L ₁₂ type Al ₃ Zr together with Zr and six other specific alloy elements. And it dissolves also in this intermetallic compound and Al matrix, and improves heat-resistant strength and abrasion resistance. If the amount is less than the lower limit of 0.5%, a sufficient amount (number) of intermetallic compounds or solid solution amounts in the intermetallic compound or Al matrix cannot be obtained, and the above characteristics such as heat resistance and wear resistance are improved. Can not. On the other hand, if the upper limit of 5% is exceeded, a coarse compound is formed and, on the contrary, these properties are inhibited. Therefore, the range of Si content is 0.5 to 5%.

(V)
V forms a stable intermetallic compound such as L ₁₂ type Al ₃ Zr together with Zr and six other specific alloy elements. And it dissolves also in this intermetallic compound and Al matrix, and improves heat-resistant strength and abrasion resistance. If the amount is less than the lower limit of 0.5%, a sufficient amount (number) of intermetallic compounds or solid solution amounts in the intermetallic compound or Al matrix cannot be obtained, and the above characteristics such as heat resistance and wear resistance are improved. Can not. On the other hand, if the upper limit of 5% is exceeded, a coarse compound is formed and, on the contrary, these properties are inhibited. Therefore, the range of V content is 0.5 to 5%.

(Total of 8 elements)
In the present invention, the amount of stable intermetallic compound formation such as L ₁₂ type Al ₃ Zr and the solid solution amount of alloy elements in the intermetallic compound and Al matrix are ensured, and the heat resistance and wear resistance are reliably improved. In order to achieve this, it is further defined by the sum of these eight kinds of alloy elements such as Zr, Fe, Cr, Mn, Ti, Ni, Si, and V. That is, the total of the content of these eight elements (the total content of these eight elements) is defined as 15 to 35%.

  In the Al-based alloy of the present invention composed of a metal Al matrix and an intermetallic compound phase, the metal Al matrix is soft and the intermetallic compound phase is hard. Therefore, the Al-based alloy of the present invention has a structure in which hard intermetallic compound phases are dispersed in such a soft metal Al matrix. This hard intermetallic compound phase becomes the main phase for imparting heat resistance and wear resistance to the Al-based alloy. On the other hand, the soft metal Al matrix serves as a binder for these hard intermetallic compound phases or serves as a hard foundation for exerting the function of the intermetallic compound phases.

  The functions of these intermetallic compound phases and the metal Al matrix are more exhibited when the alloy elements are dissolved in the intermetallic compound phase and the Al matrix phase. Therefore, if the total content of the above eight elements is less than 15%, the amount of solid solution of the alloy element in the intermetallic compound phase and the Al matrix is insufficient.

  On the other hand, when the sum of the above eight elements exceeds the upper limit of 35%, an intermetallic compound phase and a structure in which any alloy element is dissolved in this intermetallic compound phase or Al matrix can be obtained. Even so, the toughness is reduced and the heat resistance strength of the Al-based alloy is reduced.

Hereinafter, other selective additive elements will be described.
(One or two of Cu and Mg)
Both Cu and Mg form an intermetallic compound together with the above eight elements, and improve the heat resistance and wear resistance by forming a solid solution in the intermetallic compound phase or the Al matrix phase. Cu and Mg have these effects when contained at 0.5% or more. However, if Cu exceeds 5% and Mg exceeds 3%, a coarse compound is formed, and the heat resistance strength is lowered. Therefore, the range of content when selectively including one or two of Cu and Mg is Cu: 0.5 to 5%, and Mg: 0.5 to 3%.

(One or more of Nd, Sc and Ag)
Nd, Sc and Ag together with the above eight elements form an intermetallic compound and improve the heat resistance strength (heat resistance). Nd is contained in an amount of 0.2% or more, and Sc and Ag are each contained in an amount of 0.1% or more. However, when Nd, Sc, and Ag each exceed 2%, the heat resistance strength and toughness are deteriorated. Therefore, the range of the content in the case of selectively containing one or more of these is Nd: 0.2-2%, Sc: 0.1-2%, Ag: 0.1-0.1 The range is 2%.

(Volume fraction of intermetallic compound phase)
FIG. 1 is a 2000-magnographic SEM photograph of an Al-based alloy of the present invention (Invention Example 1 of Examples described later). In FIG. 1, many white particle | grain parts are intermetallic compounds, and these aggregates are intermetallic compound phases. On the other hand, the black (pattern) portion is a matrix (matrix) portion of metal Al.

  As shown in FIG. 1, in the Al-based alloy of the present invention, the volume fraction of the intermetallic compound phase is increased to 35% or more, so that a plurality of (individual) intermetallic compounds (particles) are aggregated adjacent to each other. It can be seen that (continuous), that is, an intermetallic compound phase is formed. In other words, the Al matrix portion is finely divided (partitioned) by the intermetallic compound phase. Such a structural state ensures the heat resistance strength and wear resistance of the Al-based alloy.

  In an Al-based alloy, if the volume fraction of the intermetallic compound phase formed by the above alloy elements is too small, these intermetallic compound phases are insufficient, while the volume fraction of the Al matrix portion increases, and the Al The heat resistance and wear resistance of the alloy are reduced. On the other hand, when the volume fraction of these intermetallic compound phases is too large, a coarse compound is formed, and on the contrary, heat resistance and wear resistance are lowered. Further, the amount of the Al matrix portion becomes too small, and the toughness of the Al-based alloy is lowered and becomes brittle. For this reason, it cannot be used as a heat-resistant Al-based alloy. Therefore, these intermetallic compound phases are present in the Al-based alloy structure so as to occupy 35 to 80%, preferably 40 to 75% in volume fraction.

(Average size of intermetallic compounds)
In the present invention, in order to improve the heat resistance and wear resistance of the Al-based alloy, the average size of the intermetallic compound present in the Al-based alloy structure is preferably refined to 7 μm or less. Thus, when the average size of the intermetallic compound is refined, the toughness of the Al-based alloy is also improved. More preferably, it is 4.5 μm or less.

  In the present invention, as the content of each alloy element and the amount of intermetallic compounds increase, the heat resistance strength improves. However, on the other hand, the influence on the toughness of the average size of the intermetallic compound is larger than that of the Al-based alloy having a small amount of alloying element or intermetallic compound. In this respect, when the average size of the intermetallic compound is larger than 7 μm, the characteristics and toughness of the Al-based alloy may be lowered even if the above requirements are satisfied.

(Measurement of average intermetallic compound size)
The average size of the intermetallic compound (intermetallic compound particles) was measured using EDX with a TEM (transmission electron microscope) of 5000 to 15000 times. That is, the intermetallic compound is traced from the observed tissue image in the TEM field of view, and the center-of-gravity diameter of each intermetallic compound is obtained and averaged using Image-ProPlus made by MEDIACYBERNETICS as image analysis software. Asked. The number of visual fields to be measured was 10, and the average size of each visual field was further averaged to obtain the average size of the intermetallic compound.

(Al-Zr intermetallic phase)
In the present invention, when manufactured by a rapid solidification method, a stable Al—Zr-based intermetallic compound phase such as L ₁₂ type Al ₃ Zr is formed in the metal structure of the Al-based alloy. Specifically, the Al—Zr-based intermetallic compounds include, for example, L ₁₂ type (fcc structure) Al ₃ Zr, D 0 ₂₃ type (tetragonal structure) Al ₃ Zr, Al ₂ Zr, Al ₃ Zr ₂ , AlZr, to form an _{Al 4 Zr 5, Al 2 Zr} 3, AlZr 2, AlZr 3 intermetallic compound such. In the present invention, these Al—Zr-based intermetallic compounds are analyzed by the analysis method described later, and the metal having the highest Zr content except for Al among constituent elements (analytical elements) of the intermetallic compounds. The intermetallic compound is defined as an Al—Zr intermetallic compound.

  By using such an Al—Zr intermetallic compound as the main phase, the heat resistance and wear resistance of the Al-based alloy are improved.

(Solubility in Al-Zr intermetallic phase)
In the present invention, one or more of Fe, Cr, Mn, Ti, Ni, Si, V as alloy elements are dissolved in the Al-Zr intermetallic compound phase, and these are dissolved. The total sum of elements is 7% by mass or more.

  When one or more of Fe, Cr, Mn, Ti, Ni, Si, V as alloy elements are dissolved in the Al-Zr intermetallic compound phase, and these elements are not dissolved in the intermetallic compound phase As compared with the above, the strength, toughness, and hardness (heat resistance strength, wear resistance) of the Al—Zr-based intermetallic compound and the Al-based alloy can be remarkably improved.

  In order to exert this effect, the total amount of solid solution of Fe, Cr, Mn, Ti, Ni, Si, V in the Al—Zr-based intermetallic compound phase is 7% by mass or more, preferably Must be 10% by mass or more. If the total sum of these alloy elements in solid solution is less than 7% by mass, the effect of improving the strength, toughness, and hardness (heat resistance strength, wear resistance) of the Al-based alloy is not sufficient. The upper limit of the solid solution amount is determined from the solid solution limit of these alloy elements, and is not particularly specified.

  In the case where the Al-based alloy further includes one or two of Cu and Mg in addition to Fe, Cr, Mn, Ti, Ni, Si, and V, the total amount of solid solution of each alloy element Is the sum of the solid solution amounts of the alloy elements of Fe, Cr, Mn, Ti, Ni, Si, and V to which these Cu and Mg are added. In this case, the total sum of these alloy elements dissolved is 9% by mass or more.

  In addition, in addition to Fe, Cr, Mn, Ti, Ni, Si, V, the Al-based alloy further includes one or more of Nd, Sc, and Ag, these Nd, Sc, Sum of solid solution amounts of alloy elements of Fe, Cr, Mn, Ti, Ni, Si, V with addition of Ag, or alloy elements of Fe, Cr, Mn, Ti, Ni, Si, V, Cu, Mg The total amount of solid solution. In this case, the total sum of these alloy elements dissolved is 10% by mass or more.

(Method for measuring the amount of solid solution in the Al-Zr intermetallic compound phase)
Measurement of the solid solution amount of the alloy element in the Al—Zr-based intermetallic compound phase is 5,000 to 15,000 times TEM (transmission electron microscope) and 45,000 times EDX (manufactured by Kevex, Sigma energy dispersion) accompanying this TEM. A type X-ray detector (energy dispersive X-ray spectrometer) is used. That is, with these analytical instruments, among the intermetallic compounds containing Zr in the TEM field of view, the intermetallic compound showing the highest value of the Zr content is excluded from the Al-Zr intermetallic compound, except for Al. Identify. Then, for example, 10 points of each of the identified Al—Zr-based intermetallic compounds are arbitrarily selected, and the total amount of the solid solution of the above-described elements in each of the Al—Zr-based intermetallic compounds is measured. Is averaged.

(Solution of each element in metallic Al)
In addition to the solid solution in the Al-Zr-based intermetallic compound phase described above, the total amount of each solid solution alloy element is also dissolved in the metal Al matrix by 0.5 to 15% by mass, so that the metal Al matrix can be dissolved. Even when the strength is increased and the metal Al matrix is used for a heat-resistant machine component, a hard intermetallic compound phase can be held on the surface, and the wear resistance of the Al-based alloy can be improved.

  When the total solid solution amount of each solid solution alloy element is less than 0.5% by mass, the strength of the metal Al matrix increases to the extent that a hard intermetallic compound phase can be held on the surface when used in heat-resistant machine parts. do not do. On the other hand, when the total amount of the solid solution of each alloy additive element exceeds 15% by mass, the metal Al matrix becomes brittle, the toughness is lowered, and cannot be used as a heat-resistant machine part.

  In the case where the Al-based alloy further includes one or two of Cu and Mg in addition to Fe, Cr, Mn, Ti, Ni, Si, and V, the total amount of solid solution of each alloy element Is the sum of the solid solution amounts of the alloy elements of Fe, Cr, Mn, Ti, Ni, Si, and V to which these Cu and Mg are added. In this case, the total sum of these alloy elements dissolved is 0.5 to 20% by mass.

  In addition, in addition to Fe, Cr, Mn, Ti, Ni, Si, V, the Al-based alloy further includes one or more of Nd, Sc, and Ag, these Nd, Sc, Sum of solid solution amounts of alloy elements of Fe, Cr, Mn, Ti, Ni, Si, V with addition of Ag, or alloy elements of Cu, Mg, Fe, Cr, Mn, Ti, Ni, Si, V The total amount of solid solution. In this case, the total sum of these alloy elements dissolved is 0.5 to 22% by mass or more.

(Evaluation method of solid solution amount in Al matrix)
The measurement of the solid solution amount of the alloy-added element in the metal Al matrix is the same as the measurement of the solid solution amount of the alloy-added element in the Al-Zr intermetallic compound phase. 45,000 times EDX attached to this TEM (manufactured by Kevex, Sigma energy dispersive X-ray detector: energy
dispersive X-ray spectrometer) is used. Then, with these instruments, for example, 10 points of metal Al matrix in the TEM visual field are arbitrarily selected, and the total amount of the solid solution of the elements is measured and averaged.

(Production method)
Below, the manufacturing method of this invention Al group alloy is demonstrated.

  The Al-based alloy of the present invention has a large amount of alloying elements and precipitates a large amount of intermetallic compound phases, so that it is difficult to produce by an ordinary melt casting method (ingot making). For this reason, the Al-based alloy of the present invention is obtained by a rapid solidification method. As the rapid solidification method, a known method such as a rapid powder metallurgy method, a spray forming method, or a twin roll method is appropriately selected.

  In the rapid powder metallurgy method, the Al alloy powder obtained by rapid solidification is densified by CIP or HIP treatment, and then hot-worked (plastic working) such as forging, extrusion, or rolling. In the spray forming method, a preform obtained by rapid solidification is obtained as it is or after being densified by CIP or HIP treatment, and then subjected to hot working such as forging, extrusion, and rolling. In the twin roll method, the plate-shaped ingot obtained by rapid solidification can be obtained as it is or by further processing such as cold rolling.

  According to these rapid solidification methods, the cooling / solidification rate is much faster than that of the ordinary melting and casting method. For this reason, by these rapid solidification methods, the Al-based alloy structure can be made into a fine Al—Zr-based intermetallic compound phase in which alloy elements are dissolved or a metal Al matrix in which alloy elements are dissolved.

  In any rapid solidification method, it is necessary to optimize the dissolution conditions and the cooling / solidification rate. In a preferred embodiment, the Al alloy having the composition of the present invention is melted at a melting temperature of 1250 to 1600 ° C., and then the molten metal is heated to a rapid solidification start temperature such as supply between sprays or twin rolls at 200 ° C./h. Cooling is performed at the above cooling rate, and then, at 900 to 1200 ° C., rapid solidification such as spraying or supplying between the two rolls is started, and then quenched powder (quenched powder metallurgy method) or preform body ( A spray forming method) and a thin plate ingot (a twin roll method) are produced.

(Melting temperature)
The reason why the melting temperature is set to 1250 ° C. or higher is to once completely dissolve each intermetallic compound phase in the Al alloy having the composition of the present invention. In addition, as the content of each alloy element is larger, in order to completely dissolve each intermetallic compound phase, the melting temperature is preferably higher than 1250 ° C., but the temperature exceeding 1600 ° C. There is no need to do.

(Rapid solidification start temperature)
When starting the rapid solidification of the molten metal, preferably, the molten metal is cooled to a rapid solidification start temperature at a cooling rate of 200 ° C./h or more, and then the rapid solidification of the molten metal is started at 900 to 1200 ° C. The melting at the high temperature is to completely dissolve the intermetallic compound phase, but here the cooling solid is once cooled and then the rapid solidification is started to crystallize the intermetallic compound to some extent, This is because there is an effect of finely crystallizing other intermetallic compounds during rapid solidification using the crystallized intermetallic compounds as nuclei. Moreover, when the rapid solidification is started from a low temperature, there is an effect that the cooling rate of the rapid solidification is increased and the intermetallic compound to be crystallized is further refined.

  More specifically, by pattern control for cooling the molten metal to a rapid solidification start temperature at a cooling rate of 200 ° C./h or more, first, Al—Cr that is effective for refinement of intermetallic compounds by the start of rapid solidification. The Al—Fe intermetallic compound is crystallized to some extent, and this is used as a nucleus to finely crystallize the Al—Zr intermetallic compound during rapid solidification. If this pattern control is not performed, the crystallized intermetallic compound may not be refined.

  In addition, when the cooling rate to the rapid solidification start temperature of the molten metal is less than 200 ° C./h, the above-described intermetallic compound cannot be finely crystallized, and the intermetallic compound to be crystallized may not be miniaturized. Is expensive.

  The rapid solidification start temperature of the molten metal affects the cooling and crystallization speed in the rapid solidification process. In other words, the rapid solidification start temperature of the molten metal tends to increase the cooling rate when the temperature is low. However, when the rapid solidification start temperature is less than 900 ° C., an intermetallic compound crystallizes in the molten metal before the rapid solidification process, and the molten metal supply means such as a nozzle is likely to be blocked. On the other hand, when the rapid solidification start temperature exceeds 1200 ° C., the cooling rate during the rapid solidification process becomes slow, and the intermetallic compound tends to become coarse.

  In the rapid solidification process, it is important to sufficiently increase the cooling rate. When the cooling rate is sufficiently high, the frequency of crystallization nucleation of the intermetallic compound increases, so that coarsening of the intermetallic compound particles can be prevented and the intermetallic compound phase can be refined. Further, since the intermetallic compound particles are made fine, the frequency of contact with adjacent grains is reduced, and the outer dimensions of the intermetallic compound phase can be reduced.

(Cooling conditions for twin rolls)
In the case of obtaining a thin plate-shaped ingot by the twin roll method, the cooling ability of the twin roll composed of a pair of rotating roll molds is important. For this reason, use a copper water-cooled roll mold having a higher heat transfer coefficient than a water-cooled roll mold made of steel or stainless steel to ensure a cooling rate of 50 ° C./s or more when casting with a twin roll. Is preferred.

(Cooling conditions with gas)
The cooling rate in the rapid solidification process by atomization in the rapid powder metallurgy method or spraying in the spray forming method is, for example, in the case of rapid cooling with gas (gas), the gas / metal ratio (G / M ratio: sprayed on the molten metal per unit mass) Gas amount). The higher the G / M ratio, the faster the cooling rate, the fine intermetallic compound phase as defined in the present invention can be obtained, and a predetermined amount of each element can be dissolved in the metal Al matrix. In addition, elements other than those constituting the above-described intermetallic compound can be forcibly dissolved in the intermetallic compound phase.

If the G / M ratio is too low, the cooling rate will be insufficient, and a predetermined amount of each element cannot be dissolved in the metal Al matrix. In addition, elements other than those constituting the above-described intermetallic compound cannot be forcibly dissolved in the intermetallic compound phase. Also, the intermetallic compound phase becomes coarse. However, if the G / M ratio is too high, the yield decreases. It is recommended that the lower limit of the G / M ratio satisfying these conditions is 6 Nm ³ / kg or more, and the upper limit of the G / M ratio is 20 Nm ³ / kg or less.

  When producing the Al-based alloy of the present invention by the quenching powder metallurgy method, among the atomized powders of the Al alloy having the composition of the present invention, fine particles having an average particle size of 20 μm or less, preferably 10 μm or less are classified and used. It is preferable. Atomized powder having an average particle size exceeding 20 μm has a slow cooling rate, so that the intermetallic compound phase becomes coarse. For this reason, when an atomized powder having an average particle size exceeding 20 μm is used, there is a high possibility that the Al-based alloy of the present invention cannot be produced. For this reason, only the fine powder having an average particle diameter of 20 μm or less is solidified and molded by CIP processing or HIP processing, and further HIP processing after CIP, thereby obtaining the Al alloy preform.

(Hot processing)
In order to make the Al alloy preform body of the rapidly cooled powder or the spray-formed Al alloy preform body produced in this way to be further densified and shaped into products, it is hot forging, extrusion, rolling, etc. Preferably it is processed.

  By these hot working (plastic working), the intermetallic compound phase in the Al-based alloy structure is more finely and uniformly dispersed, and the solid solution amount of each element in the metal Al matrix is further ensured. The processing temperature in the hot processing of forging, extrusion, and rolling is set to a range of 500 to 620 ° C. However, in order to ensure the solid solution amount in the metal Al matrix, it is preferable to make it relatively low. When hot working in such a working temperature range, the intermetallic compound phase is further refined and more uniformly dispersed. Moreover, the solid solution amount in the Al matrix is further secured.

  When the processing temperature in the hot processing exceeds 620 ° C., the intermetallic compound phase is precipitated, and it becomes impossible to secure the solid solution amount in the Al matrix, and the intermetallic compound phase is likely to be coarsened. On the other hand, when the processing temperature is less than 500 ° C., the above-described intermetallic compound refinement effect by hot working cannot be achieved.

For the same purpose, it is preferable that the strain rate in the hot working is relatively low, 10 ⁻⁴ to 10 ⁻¹ (1 / s). If the strain rate is too large, the above-mentioned effect by hot working cannot be achieved. Also, if the strain rate is too low, the intermetallic compound phase precipitates, and it becomes impossible to secure the solid solution amount of the additive element dissolved in the Al matrix, and the intermetallic compound phase may become coarse. Is expensive.

  The Al-based alloy thus hot-worked is used as it is or after appropriate processing such as machining to obtain a product Al-based alloy.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, but may be appropriately modified within a range that can meet the purpose described above and below. Of course, it is possible to implement them, and they are all included in the technical scope of the present invention.

The molten alloys of the Al alloys having the respective component compositions shown in Table 1 below are commonly melted at respective melting temperatures of 1300 to 1600 ° C., and the molten metal is cooled to a gas atomization start temperature at a cooling rate of 100 ° C./h or more. Thereafter, N ₂ gas atomization of this molten metal was started at 900 to 1400 ° C., and Al alloy powders were produced at respective G / M ratios of 2 to 15. Table 2 also shows these gas atomization conditions (dissolution temperature, atomization start temperature, average G / M ratio: unit is Nm ³ / kg) in each of the inventive examples and comparative examples.

  Among the obtained Al alloy powders, fine particles having an average particle size of 20 μm or less are classified, loaded into a SUS can, and reduced in pressure to 13 KPa (100 Torr) or less at a temperature of 400 ° C. for 2 hours. Holding and degassing, the can was sealed to form a capsule. The obtained capsule was CIP-treated [temperature: normal temperature, pressure: 100 MPa (1000 atm), holding time: 2 hours] to obtain a preform. These preforms were hot forged under the conditions shown in Table 2 to obtain a round bar-shaped Al-based alloy (test material).

  The structure and characteristics of these Al-based alloys (test materials) were measured and evaluated as follows. These results are shown in Table 3, respectively.

(Volume fraction of intermetallic compound phase)
As for the volume fraction of the intermetallic compound phase of the Al-based alloy structure, the structure of the Al-based alloy with 10 fields of view having a size of about 60 μm × about 40 μm was observed with an SEM of 2000 times. Then, by using EDX to distinguish between the metallic Al phase and the intermetallic compound phase of the tissue in the field of view that has been photographed or processed by the reflected electron image, the volume fraction of the intermetallic compound phase in each field of view. Were measured and averaged over 10 fields of view.

(Average size of intermetallic compounds)
The average size of the intermetallic compound (intermetallic compound particles) was measured using EDX with a TEM (transmission electron microscope) of 5000 to 15000 times. That is, the intermetallic compound is traced from the observed tissue image in the TEM field of view, and the center-of-gravity diameter of each intermetallic compound is obtained and averaged using Image-ProPlus made by MEDIACYBERNETICS as image analysis software. Asked. The number of visual fields to be measured was 10, and the average size of each visual field was further averaged to obtain the average size of the intermetallic compound.

(Element solid solution amount in the Al-Zr intermetallic phase)
Each intermetallic compound phase in the visual field is analyzed from the electron diffraction pattern of X-ray diffraction and TEM, and the crystal structure of the intermetallic compound in the intermetallic compound phase is analyzed, and the content of Zr excludes Al. The highest Al—Zr intermetallic phase compared with other elements was identified and distinguished from other intermetallic compounds.

  On top of that, FE-TEM (HF-2000 field emission transmission electron microscope, manufactured by Hitachi, Ltd.) and 45,000 times EDX (manufactured by Kevex, Sigma energy dispersive X-ray) attached to this TEM. A detector: energy dispersive X-ray spectrometer) was used to measure 10 Al-Zr intermetallic phases in the field of view. And the sum total of the solid solution amount to the intermetallic compound phase of Fe, Cr, Mn, Ti, Ni, Si, V, Cu, Mg, Nd, Sc, and Ag was obtained and averaged. In each example, all of these elements contained in each specified range were dissolved in the Al—Zr intermetallic compound phase.

(Element solid solution amount in Al matrix)
In each of the examples, the solid solution amount measurement method by TEM-EDX described above was used for the solid solution of Zr, Fe, Cr, Mn, Ti, Ni, Si, V, Cu, Mg, Nd, Sc, and Ag in metal Al. The total amount of solution was determined. In each example, all of these elements contained in each specified range were dissolved in the Al matrix.

(Strength)
In order to evaluate the heat resistance of the Al-based alloy, the strength at room temperature and high temperature was measured. Each Al-based alloy test piece having a parallel part Φ4 × 15 mmL was heated at room temperature (15 ° C.) and the high-temperature strength was 300 ° C. and 400 ° C. and held at this temperature for 15 minutes. A tensile test was performed. The tensile speed was 0.5 mm / min, and the strain speed was 5 × 10 ⁻⁴ (1 / s). The high-temperature tensile strength was evaluated as having passed high-temperature strength or heat resistance when the tensile strength was 280 MPa or higher at 300 ° C. and 200 MPa or higher at 400 ° C.

(Toughness)
Since the toughness of the material is generally correlated with the Vickers hardness, the room temperature strength and the high temperature strength of the material were evaluated by the Vickers hardness. That is, the Vickers hardness at room temperature and high temperatures of 300 ° C. and 400 ° C. were measured under conditions of a load of 5 kgf (in the case of room temperature) and a load of 1 kgf (in the case of high temperature). The Vickers hardness was evaluated as having heat resistance when the Vickers hardness at a temperature of 300 ° C. was 180 HV or higher and the Vickers hardness at a temperature of 400 ° C. was 100 HV or higher.

  Furthermore, the permanent indentation (indentation) of the material whose Vickers hardness was measured at 400 ° C. was observed by SEM (magnification: 500 times), and the presence of cracks around the indentation (indentation) where the hardness was measured was examined. The toughness (heat resistance) of was evaluated. That is, the case where no crack was generated was evaluated as “good” as having toughness (heat resistance). On the other hand, those having cracks were evaluated as x with no toughness (heat resistance).

(Abrasion resistance)
The high temperature wear resistance test of the Al-based alloy was conducted by a pin-on-disk wear test. Each test material was set on a pin material (Φ7 mm × 15 mm length, about 1 g), and the test disk material on the wear partner side was FC200 (cast iron). The test temperature was 200 ° C., the load was 10 kgf, the rotation radius of the pin was 0.02 m, and the test material was brought into contact with the rotating test disk material for 10 minutes without lubrication. The mass reduction rate due to wear of each test material at this time, (mass before test−mass after test) / mass before test of the test material was evaluated. When the wear reduction rate of this mass is 0.2 g or less, the wear resistance at high temperature is evaluated as “good”, and when the wear reduction rate exceeds 0.2 g, the wear resistance at high temperature is poor. It evaluated as x as a pass.

  As is apparent from Tables 1 to 3, Invention Examples 1 to 12 satisfy both the alloy element amount ranges defined in the present invention and the total range of these alloy element amounts. Also, structurally, it has an Al—Zr-based intermetallic compound phase and satisfies the volume fraction regulation of the intermetallic compound phase. Furthermore, one or more of Fe, Cr, Mn, Ti, Ni, Si, V, Cu, Mg, Nd, Sc, and Ag are dissolved in the Al—Zr-based intermetallic compound phase. The total of dissolved elements is 7% or more.

  In addition, except for Invention Example 3, the total amount of element solid solutions of Zr, Fe, Cr, Mn, Ti, Ni, Si, V, Cu, Mg, Nd, Sc, and Ag in the Al matrix is 0.00. It is 5 to 15% of range. Furthermore, except for Invention Example 2, the average size of the intermetallic compound is preferably within the upper limit of 7 μm.

  For this reason, Invention Examples 1 to 12 are excellent in high temperature strength and high temperature wear resistance, as apparent from Table 3, except for Invention Examples 2 and 3.

  In Invention Example 2, the average size of the intermetallic compound is coarsened exceeding the preferred upper limit. As a result, Invention Example 2 has relatively low high-temperature strength and high-temperature wear resistance as compared with other Invention Examples.

  In Invention Example 3, the total amount of alloying elements dissolved in the Al matrix is less than the preferred lower limit of 5%. As a result, Invention Example 3 has relatively low high-temperature strength and high-temperature wear resistance as compared with other Invention Examples.

  On the other hand, Comparative Examples 13-24 are each alloy element amount range prescribed | regulated by this invention, the range of the sum total of these each alloy element amount, volume fraction regulation of an intermetallic compound phase, this Al-Zr type intermetallic compound phase One of the total amount of alloying elements dissolved in is off.

  For this reason, Comparative Examples 13 to 24 have lower high-temperature strength and high-temperature wear resistance than the inventive examples.

Although Comparative Examples 16 to 24 are manufactured under preferable manufacturing conditions, they are out of the alloy element amount range defined in the present invention.
In Comparative Example 16, the Zr content of Alloy Example I in Table 1 is below the lower limit.
In Comparative Example 17, the Zr content of Alloy Example J in Table 1 exceeds the upper limit.
In Comparative Example 18, Alloy Example K in Table 1 does not contain essential Fe (Fe-less).
In Comparative Example 19, Alloy Example L in Table 1 does not contain essential Cr (Cr-less).
In Comparative Example 20, the alloy example M in Table 1 does not contain essential Mn (Mn-less).
In Comparative Example 21, Alloy Example N in Table 1 does not contain essential Ti (Ti-less).
In Comparative Example 22, the alloy example O in Table 1 does not contain essential Ni (Ni-less).
In Comparative Example 23, Alloy Example P in Table 1 does not contain essential Si (Si-less).
In Comparative Example 24, Alloy Example Q in Table 1 does not contain essential V (V-less).

  From the above results, the critical significance of each requirement and preferred requirement of the present invention for improving the high temperature strength and the high temperature wear resistance is supported.

  As described above, the present invention can provide a heat-resistant Al-based alloy that is lightweight and has high heat resistance and high wear resistance in the vicinity of 300 to 400 ° C. Therefore, the present invention can be applied to various parts that require heat resistance such as engine parts (piston, connecting rod) such as automobiles and airplanes.

It is a drawing substitute photograph which shows the structure | tissue of this invention Al base alloy.

Claims (9)

  In mass%, Zr: 5 to 15%, Fe: 1 to 8%, Cr: 1 to 8%, Mn: 1 to 8%, Ti: 0.5 to 5%, Ni: 0.5 to 5% , Si: 0.5 to 5%, V: 0.5 to 5%, respectively, and the total content of these elements is 15 to 35%, the balance being Al and inevitable impurities Al The Al-based alloy structure is composed of an intermetallic compound phase with a volume fraction of 35 to 80% and a balance of a metal Al matrix, and the intermetallic compound phase structure contains an Al-Zr-based structure. While having an intermetallic compound phase, one or more of Fe, Cr, Mn, Ti, Ni, Si, and V are in solid solution in the Al-Zr intermetallic compound phase, and these dissolved elements Is a heat-resistant Al-based alloy, characterized in that the total amount of   In the metal Al matrix, at least one of the elements Zr, Fe, Cr, Mn, Ti, Ni, Si, and V is dissolved in a total amount of 0.5 to 15% by mass. The heat-resistant Al-based alloy according to claim 1.   3. The heat-resistant Al-based alloy according to claim 1, wherein an average size of intermetallic compounds existing in the Al-based alloy structure is 7 μm or less.   The heat-resistant Al according to any one of claims 1 to 3, wherein the Al-based alloy further contains one or two of Cu: 0.5 to 5% and Mg: 0.5 to 3%. Base alloy.   One or two kinds of Cu and Mg are further solid-dissolved in the Al-Zr intermetallic compound phase, and the total of the solid-solved elements including Cu and Mg is 9% by mass or more. The heat resistant Al-based alloy according to claim 4.   5. The metal Al matrix further comprises one or two of Cu and Mg in a solid solution of 0.5 to 20% by mass as a total of the solid solution elements to which Cu and Mg are added. Or the heat-resistant Al-based alloy according to 5;   The Al-based alloy further includes one or more of Nd: 0.2 to 2%, Sc: 0.1 to 2%, and Ag: 0.1 to 2%. 2. A heat-resistant Al-based alloy according to item 1.   Nd, Sc, and Ag are further dissolved in the Al-Zr-based intermetallic compound phase, and the total of the dissolved elements including Nd, Sc, and Ag is 10% by mass or more. 8. A heat-resistant Al-based alloy according to 7.     In the metal Al matrix, one or more of Nd, Sc, and Ag are solid-dissolved in a total amount of 0.5 to 22% by mass as a total of the solid-solved elements to which these Nd, Sc, and Ag are added. The heat-resistant Al-based alloy according to claim 7 or 8.

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