JPS6117898B2

JPS6117898B2 -

Info

Publication number: JPS6117898B2
Application number: JP8379278A
Authority: JP
Inventors: Naoharu Fujimori; Takeshi Asai; Takaharu Yamamoto
Original assignee: Sumitomo Electric Industries Ltd
Current assignee: Sumitomo Electric Industries Ltd
Priority date: 1978-07-10
Filing date: 1978-07-10
Publication date: 1986-05-09
Also published as: JPS5511158A

Description

[Detailed description of the invention]

本発明は強靭で耐摩耗性に優れた焼結高融点金
属に関する。Ｗ、Moを代表とする高融点金属は非酸化性の
雰囲気における耐熱性は良い性質を持つていなが
ら現在ではその使用は必ずしも多くはない。これ
はＷやMoは比較的高価であるだけでなく製品の
加工性あるいは強度において問題があつたからで
ある。Ｗ、Moは高い融点を持つがゆえに溶解鋳
造といつた金属材料において一般的に使われてい
る製造上の技法を使うことは通常の金属に比して
著しく困難である。従つて、このような場合には粉末冶金法が適し
ていると考えられるが、前述と同じようにＷ、
Mo等は融点が高いことによつて焼結性も劣り焼
結により得られたＷあるいはMoは脆弱であり、
多くの場合高温での使用には耐えられない。そこ
で合金化あるいは分散強化型合金への工夫、更に
は加工を加えて使用する等が試みられてきた。発明者はこれ等の高融点金属の欠点につき詳細
に検討を行つて強靭で且つ耐熱性を有する合金を
考えつくに至つた。以下この考え方を述べる。ＷあるいはMo中に炭化物あるいは窒化物を入
れて分散強化した合金はこれまでもいくつか考え
られてきた。その代表的なものは米国特許第3690962号に提
案のＷ−Ti−Ｃ系鋳造合金である。これはＷ−
Ti−Ｃ三元素において融点の低い組成を選んで
特殊な溶解法によつて合金を作成するとの提案で
ある。本法によればＷのマトリツクスにTiCが層
状に分散してミクロ的には極めて強靭な合金とな
る。しかし本方法は２つの本質的問題を持つてい
た。その第１は融点の低い成分を作ることを主眼
としており、その組成はＷ組とTiC相が１：１近
辺に限られており、耐熱性を向上させるためにＷ
の多い合金を作ろうとすると融点が高くなり実際
的に製造は困難であつた。第２の問題は、この合金には気孔が多いために
マクロ的には必ずしも強度が高くなかつたことに
ある。それではこのような系の合金が粉末冶金法
によつて作成できればこれ等２つの問題が解決さ
れ得ることは当業者であれば容易に類推できると
ころである。しかし、このような合金は実際には
製造されていない。その原因は先にも述べたよう
に主に焼結が難かしいことゝ、でき上つた焼結体
の強度が弱いことによると考えられる。発明者は
本系の合金について詳細に調査し、焼結によつて
十分な強度を得られる方法を考えつくに至つた。
それは添加する炭化物、窒化物に酸素を投入する
ことにある。本発明合金の構造について述べる。本発明合金
は高融点金属相及び硬質相より成る。この２相は
粉末冶金によつて作られるために極めて均一に分
散する。また、本発明の最大の特徴である含有酸素は殆
どが硬質相中に存在する。これらについては第２
図にW⁶⁰−Ti¹⁹−C¹⁵−O⁶の原子比率の本発明合
金のＸ線回折のパターンを示す。この図より明ら
かな如く、本発明合金はＷ相とTiC相との２相の
みしか観察されない。次に本発明の限定条件について説明する。組成範囲は第１図のABCD内においては殆ど
Ｗ、MoもしくはＷ、Mo合金相等の金属相とTiC
相になり本発明の目的に適合するが、A′B′CD′の
範囲内であれば特に耐熱性を必要とする場合良い
性質を示す。 AD，CDの線分より外側ではW₂C、Mo₂Cとい
つた脆い硬質相が析出するため好ましくない。
BCの外では硬質相の割合が少なくなり強化とい
う融点からは劣る。またABの外側では高融点金
属相が少なく耐熱性が劣る。以上の如く発明者は
実験によつて本発明の有効なる範囲を定めた。３種の成分の比率は上述の如く決定されたが、
各々の構成元素については以下のように定められ
る。先ずＣ、Ｎ、ＯついてはＮ、Ｏの如き元素が余
り増大すると、硬質相と金属相の接着が悪化する
ことは周知である。よつてＮ＋Ｏ／Ｃ＋Ｎ＋Ｏ＜0.6が
望ましい。またＮ、Ｏは各々Ｎ／Ｃ＋Ｎ＋Ｏ≦0.5 Ｏ／Ｃ＋Ｎ＋Ｏ≦0.5が焼結性の点から望ましい。しかし、本発明はＯを含有することに特徴があり
Ｏ／Ｃ＋Ｎ＋Ｏ＞0.02であれば効果が見出され、0.05≦ Ｏ／Ｃ＋Ｎ＋Ｏ≦0.3であれば効果は顕著である。Ti、 Zr、Hf等のNa族元素の比率については特に限定
範囲はないが、硬質相の強度や原料のコストを考
えるとTiが多い場合が工業的には望ましい。Ｗ、MoについてもNa族元素と同様であるが、
耐熱性はＷが優れ、耐食性に関してはMoが優れ
ている。第１図に示された元素以外に他の元素の添加に
ついても効果のあるものもある。Ni、Fe、Co等
の鉄族金属がCu、Pd、Ag等はＷ、Moの焼結を
促進し好ましいが、添加量が過大となると耐熱性
を損ねるので2.0原子％以内とすべきである。な
お、0.1原子％以下では効果が認められない。また、Nb、Ta等のａ族元素については、
ａ族元素の硬質相中に固溶して性質を改善す
る。、Nbは耐摩耗性の向上に効果があり、Ta
は強度の増加に効果を示す。しかし、これ等ａ
族元素の添加は脆いMe₂C相の出現の可能性を高
めることがよく知られており、ａ族金属／ａ
族金属＋ａ族金属の値は0.3以内に収めること
が望ましい。なお0.001以下では効果が認められ
ない。また、Crを少量添加することは周知の如く耐
食性の向上に効果があり、本発明の範囲である。
また周知の如くＷ、Mo等の強度上昇あるいは結
晶粒粗大化防止に役立つRe、ThO₂、Ｋ、Si、
Ca、Al等の添加及びＢを高融点金属相中に含有
することも又本発明合金には効果があり、本発明
の範囲である。本合金の応用は非酸化性雰囲気で耐熱性を必要
とする構造材料として有効である。更に切削工具
や耐摩工具としても本発明の合金は有効である。
特にドリル、エンドミル等の回転切削工具、鋼、
鋼用熱間ロールあるいはローラーダイス、更には
ダイキヤスト用金型としても顕著な効果を奏す
る。また、本発明合金はその耐熱性に優れることか
らも明らかなように炭化物、窒化物、酸化物等に
よる被覆工具の母材としても有用なものであり、
表面を炭化もしくは／および窒化して使用する
と、表面の耐摩耗性が向上し、母材の高靭性と相
俟つて高性能を示す。なお、耐熱材料は耐食性も厳しく要求される
が、Moを多く含有する場合はMoの酸化物の蒸気
圧が高いために耐食性は低くなるので、酸化性が
より強い雰囲気ではＷの含有が多い方が望ましい本系合金は高融点金属相中にTiCが分散されて
いるが、従来研究されてきたTiC−Ｗサーメツト
に比してはるかに金属相量が多く、またTiC相に
Ｏを含むことによつて強度が上昇し耐食性をも向
上させている。以下実施例において詳しく説明す
る。実施例１平均粒径15μのＷ粉末93重量％と平均粒径１μ
のTiC7重量％を秤取し、湿式ボールミルにて混
合し乾燥型押を行つて下記条件にて焼結を行つ
た。〜1000℃ 真空３×10^-1 Torr以下 1000℃〜1700℃ Pco 760 Torr 1700℃〜2000℃ 真空 10^-2 Torr以下以上のようにして作成された合金を分析したと
ころ、W⁶⁹−Ti¹⁵−C¹²−O⁴の組成であつた。本
合金の引張り強度は120Kg/mm²に対し、上述の焼結
工程を真空中で行つたW⁷⁰−Ti¹⁵−C¹⁵の合金の引
張強度は45Kg/mm²であつた。実施例２実施例１と同様にして表１に示した合金を作成
し、Ar雰囲気中で950℃における引張強度を比較
した。 The present invention relates to a sintered high-melting point metal that is tough and has excellent wear resistance. Although high melting point metals such as W and Mo have good heat resistance in non-oxidizing atmospheres, their use is not necessarily widespread at present. This is because W and Mo are not only relatively expensive, but also have problems with product workability or strength. Because W and Mo have high melting points, it is extremely difficult to use manufacturing techniques commonly used for metal materials, such as melting and casting, compared to ordinary metals. Therefore, powder metallurgy is considered to be suitable in such cases, but as mentioned above, W,
Due to the high melting point of Mo, etc., the sinterability is poor, and the W or Mo obtained by sintering is brittle.
In many cases, they cannot withstand use at high temperatures. Therefore, attempts have been made to create alloys or dispersion-strengthened alloys, and to use them after additional processing. The inventor conducted a detailed study on the drawbacks of these high melting point metals and came up with an alloy that is strong and heat resistant. This idea will be explained below. Several alloys have been considered so far that are dispersion-strengthened by adding carbides or nitrides to W or Mo. A typical example is the W-Ti-C cast alloy proposed in US Pat. No. 3,690,962. This is W-
The proposal is to select a composition with a low melting point among the three elements Ti-C and create an alloy using a special melting method. According to this method, TiC is dispersed in layers in a W matrix, resulting in an extremely tough alloy microscopically. However, this method had two essential problems. The first approach is to create a component with a low melting point, and its composition is limited to around 1:1 of W group and TiC phase, and in order to improve heat resistance, W
If an attempt was made to make an alloy with a large amount of carbon, the melting point would become high, making it difficult to manufacture in practice. The second problem is that this alloy does not necessarily have high strength from a macroscopic perspective because it has many pores. Those skilled in the art can easily infer that these two problems can be solved if such an alloy can be produced by powder metallurgy. However, such alloys are not actually manufactured. The reason for this is thought to be mainly due to the difficulty of sintering and the low strength of the finished sintered body, as mentioned above. The inventor investigated this alloy in detail and came up with a method for obtaining sufficient strength through sintering.
The key is to add oxygen to the added carbides and nitrides. The structure of the alloy of the present invention will be described. The alloy of the invention consists of a high melting point metal phase and a hard phase. Since these two phases are produced by powder metallurgy, they are extremely uniformly dispersed. Furthermore, most of the oxygen contained, which is the most distinctive feature of the present invention, is present in the hard phase. Regarding these, please refer to the second section.
The figure shows the X-ray diffraction pattern of the alloy of the present invention having an atomic ratio of W60- ^Ti19 ^- ^C15 - ^O6 . As is clear from this figure, only two phases, the W phase and the TiC phase, are observed in the alloy of the present invention. Next, the limiting conditions of the present invention will be explained. The composition range within ABCD in Figure 1 consists mostly of metallic phases such as W, Mo or W, Mo alloy phases, and TiC.
It forms a phase and is suitable for the purpose of the present invention, but if it is within the range of A'B'CD', it exhibits good properties especially when heat resistance is required. Outside the lines AD and CD, brittle hard phases such as W ₂ C and Mo ₂ C precipitate, which is not preferable.
Outside of BC, the proportion of hard phase decreases, making it inferior to the melting point of reinforcement. In addition, there is less high melting point metal phase on the outside of AB, and heat resistance is poor. As described above, the inventor determined the effective scope of the present invention through experiments. The ratios of the three components were determined as described above,
Each constituent element is determined as follows. First of all, regarding C, N, and O, it is well known that if the elements such as N and O increase too much, the adhesion between the hard phase and the metal phase deteriorates. Therefore, it is desirable that N+O/C+N+O<0.6. Further, from the viewpoint of sinterability, N and O are preferably N/C+N+O≦0.5 and O/C+N+O≦0.5, respectively. However, the present invention is characterized by containing O, and an effect is found when O/C+N+O>0.02, and a significant effect when 0.05≦O/C+N+O≦0.3. Although there is no particular limit on the ratio of Na group elements such as Ti, Zr, and Hf, it is industrially desirable to have a large amount of Ti, considering the strength of the hard phase and the cost of raw materials. W and Mo are similar to Na group elements, but
W has excellent heat resistance, and Mo has excellent corrosion resistance. In addition to the elements shown in FIG. 1, addition of other elements may also be effective. Iron group metals such as Ni, Fe, and Co are preferable because Cu, Pd, and Ag promote the sintering of W and Mo, but if the amount added is excessive, heat resistance will be impaired, so the amount should be within 2.0 at%. . Note that no effect is observed at 0.1 atomic % or less. In addition, regarding group a elements such as Nb and Ta,
Improves properties by solid solution in the hard phase of group a elements. , Nb is effective in improving wear resistance, and Ta
shows an effect on increasing strength. However, these a
It is well known that the addition of group elements increases the possibility of the appearance of brittle Me ₂ C phases, and the addition of group a metals/a
It is desirable that the value of group metal + group a metal be within 0.3. Note that no effect is observed below 0.001. Furthermore, addition of a small amount of Cr is effective in improving corrosion resistance, as is well known, and is within the scope of the present invention.
In addition, as is well known, Re, ThO ₂ , K, Si,
The addition of Ca, Al, etc. and the inclusion of B in the high melting point metal phase are also effective for the alloy of the present invention and are within the scope of the present invention. The application of this alloy is effective as a structural material that requires heat resistance in a non-oxidizing atmosphere. Furthermore, the alloy of the present invention is effective as a cutting tool or a wear-resistant tool.
Especially rotary cutting tools such as drills and end mills, steel,
It has remarkable effects as a hot roll or roller die for steel, and even as a mold for die casting. Furthermore, as is clear from its excellent heat resistance, the alloy of the present invention is useful as a base material for tools coated with carbides, nitrides, oxides, etc.
When the surface is carbonized and/or nitrided, the wear resistance of the surface is improved, and in combination with the high toughness of the base material, high performance is exhibited. Heat-resistant materials are also required to have corrosion resistance, but if a large amount of Mo is contained, the corrosion resistance will be low due to the high vapor pressure of the Mo oxide. This alloy has TiC dispersed in the high melting point metal phase, but it has a much larger amount of metal phase than TiC-W cermets that have been studied in the past, and the TiC phase contains O. This increases strength and improves corrosion resistance. This will be explained in detail in Examples below. Example 1 93% by weight of W powder with an average particle size of 15μ and an average particle size of 1μ
7% by weight of TiC was weighed out, mixed in a wet ball mill, dry-pressed, and sintered under the following conditions. ～1000℃ Vacuum 3×10 ^-1 Torr or less 1000℃～1700℃ Pco 760 Torr 1700℃～2000℃ Vacuum 10 ^-2 Torr or less Analysis of the alloy prepared as above revealed that W ⁶⁹ −Ti ¹⁵ − The composition was ^C12 - ^O4 . The tensile strength of this alloy was 120 Kg/mm ² , whereas the tensile strength of the W ⁷⁰ -Ti ¹⁵ -C ¹⁵ alloy, which was subjected to the above-mentioned sintering process in vacuum, was 45 Kg/mm ² . Example 2 The alloys shown in Table 1 were prepared in the same manner as in Example 1, and their tensile strengths at 950°C in an Ar atmosphere were compared.

【表】実施例３Ｗ、TiC、Co、Ni、Fe、Ag、Cu、Pdの粉末を
混合、型押しし、以下の条件で焼結を行つた。〜1000℃ 真空３×10^-1 Torr 1000〜1700℃ Pco 700 Torr 1700〜1950℃ 真空 10^-2 Torr以下表２に得られた合金と組成と、Ar雰囲気中900
℃での引張強度を示す。[Table] Example 3 Powders of W, TiC, Co, Ni, Fe, Ag, Cu, and Pd were mixed, pressed, and sintered under the following conditions. ～1000℃ Vacuum 3×10 ^-1 Torr 1000～1700℃ Pco 700 Torr 1700～1950℃ Vacuum 10 ^-2 Torr or less The alloys and compositions obtained in Table 2 and 900℃ in Ar atmosphere
Indicates tensile strength at °C.

【table】 [Brief explanation of the drawing]

第１図はM₁＝（Ｗ、Mo）、M₂＝（Ti、Zr、
Hf）、M₃＝（Ｃ、Ｎ、Ｏ）の原子比率を表わす
図。（M₁、M₂、M₃）の座標で表わすとＡ（40、25、35）Ｂ（55、40、５）Ｃ（90、５、５）Ｄ（55、10、35）の４点で囲まれる内側が本発明の範囲である。第
２図はＷ−Ti−Ｃ−Ｏの本発明合金のＸ線回折
のパターンである。図中１はＷのピークを表わし、２はTiC相のピ
ークを示す。 Figure 1 shows M ₁ = (W, Mo), M ₂ = (Ti, Zr,
Hf), a diagram showing the atomic ratio of M ₃ =(C, N, O). Expressed in the coordinates of (M ₁ , M ₂ , M ₃ ), the four points are A (40, 25, 35) B (55, 40, 5) C (90, 5, 5) D (55, 10, 35) The scope of the present invention is within the range enclosed by . FIG. 2 is an X-ray diffraction pattern of the W-Ti-C-O alloy of the present invention. In the figure, 1 represents the peak of W, and 2 represents the peak of the TiC phase.

Claims

[Claims] 1. The composition of the three element groups M ₁ , M ₂ , and M ₃ is
A heat-resistant alloy characterized by being located inside the four points A, B, C, and D in the figure. Therefore, M ₁ is Mo and/or W, M ₂ is Ti,
One or more selected from the group consisting of Zr and Hf, M ₃ consists of C and O, and the atomic ratio is 0.02≦C/C+O≦0.5. Note that A, B, C, and D are expressed in atomic percent as shown in the following table. 2. A patent claim characterized in that the compositions of the three element groups M ₁ , M ₂ , and M ₃ are within the area surrounded by the four points A', B', C, and D' in FIG. The heat-resistant alloy according to item 1. Note that A', B', C, and D' are expressed in atomic percent as shown in the following table. 3. A heat-resistant alloy characterized in that the composition of the three element groups M ₁ , M ₂ , and M ₃ is within the area surrounded by the four points A, B, C, and D in FIG. Therefore, M ₁ is Mo and/or W, M ₂ is Ti,
One or more selected from the group consisting of Zr and Hf, _M3 consists of C, N, and O, with atomic ratios of 0.02≦O/C+N+O≦0.5, 0.005≦N/C+N+O≦0.5 0.02≦N+O/C+N+O <0.6. Note that A, B, C, and D are expressed in atomic percent as shown in the following table. 4. A patent claim characterized in that the compositions of the three element groups M ₁ , M ₂ , and M ₃ are within the area surrounded by the four points A', B', C, and D' in FIG. Heat-resistant alloy according to range 3. Note that A', B', C, and D' are expressed in atomic percent as shown in the following table. 5 In a heat-resistant alloy in which the composition of the three element groups M ₁ , M ₂ , and M ₃ is within the area surrounded by the four points A, B, C, and D in Figure 1, M ₁ is Mo and/or W, _M2
is one or more selected from the group consisting of Ti, Zr, and Hf, _M3 is composed of C, N, and O, and the atomic ratio is 0.02≦O/C+N+O≦0.5, 0.005≦N/C+N+O≦0.5 0.02≦ A heat-resistant alloy in which N+O/C+N+O<0.6, and 0.1 to 30 atomic % of the _M2 element group is replaced with one or more selected from the group consisting of V, Nb, and Ta. Note that A, B, C, and D are expressed in atomic percent as shown in the following table. 6 In a heat-resistant alloy in which the composition of the three element groups M ₁ , M ₂ , and M ₃ is within the area surrounded by the four points A, B, C, and D in Figure 1, M ₁ is Mo and/or W, _M2
is one or more selected from the group consisting of Ti, Zr, and Hf, _M3 is composed of C, N, and O, and the atomic ratio is 0.02≦O/C+N+O≦0.5, 0.005≦N/C+N+O≦0.5 0.02≦ A heat-resistant alloy, characterized in that N+O/C+N+O<0.6 and containing 0.1 to 2.0 atomic percent of one or more selected from the group consisting of Ag, Cu, Fe, Ni, Co, and Pd. Note that A, B, C, and D are expressed in atomic percent as shown in the following table.