JP3865430B2 - Heat and wear resistant magnesium alloy - Google Patents
Heat and wear resistant magnesium alloy Download PDFInfo
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- JP3865430B2 JP3865430B2 JP13487396A JP13487396A JP3865430B2 JP 3865430 B2 JP3865430 B2 JP 3865430B2 JP 13487396 A JP13487396 A JP 13487396A JP 13487396 A JP13487396 A JP 13487396A JP 3865430 B2 JP3865430 B2 JP 3865430B2
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Description
【0001】
【発明の属する技術分野】
本発明は、マグネシウム合金に関し、より詳しくは自動車・二輪車用及び汎用エンジン部品などの軽量化に対応でき、これらの用途において要請されている473K程度までの高温でも十分な強度を有する、室温及び高温強度に優れた耐熱・耐摩耗性マグネシウム合金に関する。
【0002】
【従来の技術】
近年、地球環境保全の意識の高まりから、自動車の燃費向上の要請が強まり、これを実現するために自動車用軽量材料の開発が強く求められるようになってきた。
【0003】
マグネシウム合金は現在実用化されている金属材料の中で最も低密度であり、今後の自動車用軽量材料として強く期待されている。現在最も一般的に用いられているマグネシウム合金は、Mg−Al−Zn−Mn系合金(例えば、AZ91合金=Mg−9Al−1Zn−0.2Mn)であり、この合金の鋳造技術等の周辺技術は完成段階にあり、自動車軽量化にあたって、先ずこの合金が検討されている。また、耐熱用マグネシウム合金としては、マグネシウムに希土類元素(RE)を添加した合金、例えばMg−RE−Zr系合金が開発されている。
【0004】
【発明が解決しようとする課題】
しかしながら、上記のMg−Al−Zn−Mn系合金は、393K以上の高温になると急激に強度が低下し、自動車エンジン部品の中でも、耐熱性が要求される用途には適さない。また上記の耐熱性Mg−RE−Zr系合金も含めて、これらのマグネシウム合金には耐摩耗性が不足している。
【0005】
本発明は、このような従来技術の有する課題を解決するためになされたもので、耐熱性と室温強度及び耐摩耗性が要求される自動車エンジン部品用材料に適した新規な耐熱・耐摩耗性マグネシウム合金を提供することを目的としている。
【0006】
【課題を解決するための手段】
本発明者等は、上記の課題を解決するために種々検討を重ねた結果、マグネシウムに適量の珪素と希土類元素を添加することによって室温及び高温での強度及び耐摩耗性を付与できることを見出した。
【0007】
マグネシウムに希土類元素を加えることで耐熱性を向上させることは、従来からよく知られている。しかしながら、希土類元素を添加しただけでは、耐摩耗性については汎用のマグネシウム合金よりやや低下する傾向にあり、摩耗が生じる耐熱用途には適さない。ところが、所定量の珪素を添加することにより、マグネシウム及び希土類元素とのシリサイドが形成され、これにより耐摩耗性が著しく向上することを見出し、本発明を完成するに至った。
【0008】
即ち、本発明の室温、高温強度に優れ、かつ耐摩耗性にも優れたマグネシウム合金は、下記の成分
0.1重量%<希土類元素≦4重量%
0.7重量%<硅素≦5重量%
0.6重量%<亜鉛≦4重量%
を含有し、かつ
0<マンガン≦1重量%
0<ジルコニウム≦1重量%
0<カルシウム≦4.0重量%
0<アルミニウム≦10重量%
0<銀≦5重量%
からなる群から選ばれた少なくとも1種の元素を含有し、さらに下記の条件
(カルシウム+希土類元素)/(アルミニウム+亜鉛)>0.7
を満足する、
残部がマグネシウムと不可避の不純物からなることを特徴とする。
【0009】
【発明の実施の形態】
本発明の室温、高温強度に優れ、かつ耐摩耗性にも優れたマグネシウム合金においては、希土類元素はマグネシウムに固溶及びマグネシウムと金属間化合物を形成し室温および高温強度を向上させる。このような希土類元素の添加効果は、その添加量が金属間化合物を生成する0.1重量%程度から得られるが、0.5重量%以上で特に顕著になる。また、4重量%を超えると、粒界に多量の金属間化合物が晶出し、逆に室温強度を低下させるようになり好ましくない。好ましい範囲は、1重量%超〜3重量%である。
【0010】
珪素は、マグネシウム及び希土類元素と高硬度の化合物を生成し耐摩耗性を付与する。化合物は0.1重量%以上で生成するが、摩耗にはある量に達しないと効果を現わさないため0.7重量%以上が必要である。また、5重量%を超えると化合物が粗大になり室温強度を著しく低下させる。好ましい範囲は、1重量%超〜4重量%である。
【0011】
カルシウムは珪素と優先的に微細な化合物を生成し組織全体を微細化し強度を向上させる効果がある。また、カルシウムと希土類の複合添加は高温強度をさらに向上させる効果がある。また、4重量%を超えると粒界に多量の金属間化合物を晶出し、逆に室温強度を低下させるようになる。好ましい範囲は、1重量%超〜2重量%未満である。
【0012】
マンガン、ジルコニウムは、1重量%以下では一般にマグネシウムの微細化に使用されているが、同様の目的で、本発明のマグネシウム合金においても有効である。また、これらの元素は、1重量%を超えて添加しても効果は増大しない。好ましい範囲は、0.3重量%〜0.8重量%である。
【0013】
次に、アルミニウム、亜鉛、銀はいずれもマグネシウムに固溶し、室温強度を向上させる効果がある。また、アルミニウム、亜鉛は流動性を付与する効果があり、鋳造用合金、特にダイカスト用合金の主要元素となっている。本合金においても同様な効果を得ることができる。
【0014】
これらの元素の含有量としては、アルミニウムは10重量%以下、好ましくは2重量%〜7重量%である。亜鉛は5重量%以下、好ましくは0.6重量%〜4重量%である。銀は4重量%以下、好ましくは0.6重量%〜4重量%である。
【0015】
また、アルミニウムと亜鉛については、高温強度の向上について、その合計量と、希土類元素とカルシウムの合計量との間で有効な比率が存在し、とくに(カルシウム+希土類元素)/(アルミニウム+亜鉛)>0.7の条件で、特に高温強度の向上が著しい。
【0016】
【実施例】
(参考例1および比較例1〜2)
アルゴン雰囲気の真空溶解炉に、表1の組成の合金となるように原材料を装入し、溶解させた。坩堝としては鋳鉄を使用し、フラックス等は使用しなかった。その溶湯を25mm×25mm×300mmの金型中に鋳込んで試験用鋳物を作成した。このようにして得た試験用鋳物からJIS4号試験片を作成した。なお、熱処理はいずれも500K、10時間である。これらの試験片を用いて以下の試験を実施した。なおMmはミッシュメタルを表す。
【0017】
引張試験:インストロン引張試験機によりクロスヘッド速度10mm/min、測定温度298K及び473K、引張強度の測定単位=MPa、破断時伸び=%で測定。
【0018】
測定結果は表1に示す通りであった。表中の%は破断時伸びである。
【0019】
【表1】
【0020】
(比較例3〜5)
参考例1において、希土類元素および珪素に加えて、マンガン、ジルコニウムおよびカルシウムの少なくとも1種を添加した以外は同様に操作して、試験用鋳物を作成し、これらの試験片を用いて同様の試験を実施した。各試料の組成および特性をまとめて下記の表2に示す。
【0021】
【表2】
【0022】
(実施例1〜2および比較例6)
参考例1において、希土類元素および珪素に加えて、ジルコニウムおよびカルシウムの1種とともに、亜鉛または銀を添加した以外は同様に操作して、試験用鋳物を作成し、これらの試験片を用いて同様の試験を実施した。各試料の組成および特性をまとめて下記の表3に示す。
【0023】
【表3】
【0024】
表3から明らかなように、亜鉛、銀の少なくとも1種をさらに添加することにより、室温および高温強度がさらに向上していることが明らかである。
【0025】
【発明の効果】
本発明のマグネシウム合金は、従来実用されている汎用のMg−Al−Zn−Mn系合金よりも室温および高温強度及び耐摩耗性において優れており、軽量かつ耐熱性・耐摩耗性が要求される自動車エンジン部品に適した耐熱・耐摩耗性軽量マグネシウム合金である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnesium alloy, and more specifically, it can cope with weight reduction of automobiles, motorcycles, general-purpose engine parts, etc. The present invention relates to a heat-resistant and wear-resistant magnesium alloy having excellent strength.
[0002]
[Prior art]
In recent years, with the growing awareness of global environmental conservation, there has been an increasing demand for improving the fuel efficiency of automobiles, and the development of lightweight materials for automobiles has been strongly demanded to achieve this.
[0003]
Magnesium alloys have the lowest density among the metal materials currently in practical use, and are strongly expected as future lightweight materials for automobiles. Currently, the most commonly used magnesium alloy is an Mg—Al—Zn—Mn alloy (for example, AZ91 alloy = Mg-9Al-1Zn-0.2Mn), and peripheral technologies such as casting technology of this alloy. Is in the stage of completion, and this alloy is being studied first in lightening automobile weight. Moreover, as a heat-resistant magnesium alloy, an alloy obtained by adding rare earth element (RE) to magnesium, for example, an Mg-RE-Zr alloy has been developed.
[0004]
[Problems to be solved by the invention]
However, the strength of the Mg—Al—Zn—Mn based alloy rapidly decreases at a high temperature of 393 K or higher, and is not suitable for applications requiring heat resistance among automobile engine parts. In addition, these magnesium alloys, including the above heat-resistant Mg-RE-Zr-based alloys, have insufficient wear resistance.
[0005]
The present invention has been made in order to solve such problems of the prior art, and is a novel heat and wear resistance suitable for materials for automobile engine parts that require heat resistance, room temperature strength and wear resistance. The object is to provide a magnesium alloy.
[0006]
[Means for Solving the Problems]
As a result of various studies to solve the above problems, the present inventors have found that the strength and wear resistance at room temperature and high temperature can be imparted by adding appropriate amounts of silicon and rare earth elements to magnesium. .
[0007]
It has been well known that heat resistance is improved by adding rare earth elements to magnesium. However, the addition of rare earth elements tends to lower the wear resistance slightly compared to general-purpose magnesium alloys, and is not suitable for heat resistant applications where wear occurs. However, it has been found that by adding a predetermined amount of silicon, silicide with magnesium and rare earth elements is formed, whereby the wear resistance is remarkably improved, and the present invention has been completed.
[0008]
That is, the magnesium alloy having excellent room temperature and high temperature strength and excellent wear resistance according to the present invention has the following components: 0.1% by weight <rare earth element ≦ 4% by weight
0.7 wt% <silicon ≤ 5 wt%
0.6% by weight <zinc ≤ 4% by weight
And 0 <manganese ≦ 1% by weight
0 <zirconium ≦ 1% by weight
0 <calcium ≦ 4.0% by weight
0 <aluminum ≦ 10% by weight
0 <silver ≦ 5% by weight
Containing at least one element selected from the group consisting of:
(Calcium + rare earth element) / (aluminum + zinc)> 0.7
Satisfy,
The balance is made of magnesium and inevitable impurities.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
In the magnesium alloy having excellent room temperature and high temperature strength and excellent wear resistance according to the present invention, the rare earth element forms a solid solution in magnesium and forms an intermetallic compound with magnesium to improve the room temperature and high temperature strength. Such an effect of addition of rare earth elements can be obtained when the addition amount is about 0.1% by weight for forming an intermetallic compound, but becomes particularly remarkable at 0.5% by weight or more. On the other hand, if it exceeds 4% by weight, a large amount of intermetallic compounds are crystallized at the grain boundaries, and on the contrary, the room temperature strength is lowered. A preferred range is from more than 1% to 3% by weight.
[0010]
Silicon forms a high hardness compound with magnesium and rare earth elements and imparts wear resistance. The compound is produced at 0.1% by weight or more, but 0.7% by weight or more is necessary because the effect is not exhibited unless a certain amount is reached for wear. On the other hand, if it exceeds 5% by weight, the compound becomes coarse and the room temperature strength is remarkably lowered. A preferred range is from more than 1% to 4% by weight.
[0011]
Calcium has the effect of producing a fine compound preferentially with silicon and making the entire structure finer and improving the strength. The combined addition of calcium and rare earth has the effect of further improving the high temperature strength. On the other hand, if it exceeds 4% by weight, a large amount of intermetallic compounds are crystallized at the grain boundaries, and conversely, the room temperature strength is lowered. A preferred range is greater than 1 wt% to less than 2 wt%.
[0012]
Manganese and zirconium are generally used for refining magnesium at 1 wt% or less, but are also effective in the magnesium alloy of the present invention for the same purpose. Moreover, even if these elements are added in excess of 1% by weight, the effect does not increase. A preferred range is from 0.3% to 0.8% by weight.
[0013]
Next, aluminum, zinc, and silver are all dissolved in magnesium, and have the effect of improving room temperature strength. Aluminum and zinc have the effect of imparting fluidity, and are the main elements of casting alloys, particularly die casting alloys. Similar effects can be obtained with this alloy.
[0014]
As content of these elements, aluminum is 10 weight% or less, Preferably it is 2 weight%-7 weight%. Zinc is 5 wt% or less, preferably 0.6 wt% to 4 wt%. Silver is 4 wt% or less, preferably 0.6 wt% to 4 wt%.
[0015]
In addition, for aluminum and zinc, there is an effective ratio between the total amount and the total amount of rare earth elements and calcium for improving the high temperature strength, particularly (calcium + rare earth element) / (aluminum + zinc). Under the condition of> 0.7, the improvement of the high temperature strength is particularly remarkable.
[0016]
【Example】
(Reference Example 1 and Comparative Examples 1-2)
The raw materials were charged into a vacuum melting furnace in an argon atmosphere so as to be an alloy having the composition shown in Table 1 and dissolved. As the crucible, cast iron was used, and no flux was used. The molten metal was cast into a 25 mm × 25 mm × 300 mm mold to prepare a test casting. A JIS No. 4 test piece was prepared from the test casting thus obtained. In addition, all heat processing is 500K and 10 hours. The following tests were carried out using these test pieces. Mm represents misch metal.
[0017]
Tensile test: Measured with an Instron tensile tester at a crosshead speed of 10 mm / min, measurement temperatures of 298 K and 473 K, measurement unit of tensile strength = MPa, elongation at break =%.
[0018]
The measurement results are as shown in Table 1. % In the table is elongation at break.
[0019]
[ Table 1 ]
[0020]
(Ratio Comparative Examples 3-5)
In Reference Example 1, a test casting was prepared in the same manner except that at least one of manganese, zirconium and calcium was added in addition to the rare earth element and silicon, and the same test was performed using these test pieces. Carried out. The composition and characteristics of each sample are summarized in Table 2 below.
[0021]
[ Table 2 ]
[0022]
(Actual Examples 1 to 2 and Comparative Example 6)
Reference Example 1, in addition to rare earth elements and silicon, with one of di Rukoniumu and calcium, except for adding zinc or silver using the same method, to create a test casting, using these test pieces A similar test was conducted. The composition and characteristics of each sample are summarized in Table 3 below.
[0023]
[ Table 3 ]
[0024]
As apparent from Table 3, zinc, by further adding at least one silver, it is apparent that further improved room temperature and elevated temperature strength.
[0025]
【The invention's effect】
The magnesium alloy of the present invention is superior in room temperature and high temperature strength and wear resistance to general-purpose Mg-Al-Zn-Mn alloys that have been practically used, and is required to be lightweight, heat resistant, and wear resistant. A heat- and wear-resistant lightweight magnesium alloy suitable for automotive engine parts.
Claims (1)
0.1重量%<希土類元素≦4重量%
0.7重量%<硅素≦5重量%
0.6重量%<亜鉛≦4重量%
を含有し、かつ
0<マンガン≦1重量%
0<ジルコニウム≦1重量%
0<カルシウム≦4.0重量%
0<アルミニウム≦10重量%
0<銀≦5重量%
からなる群から選ばれた少なくとも1種の元素を含有し、さらに下記の条件
(カルシウム+希土類元素)/(アルミニウム+亜鉛)>0.7
を満足する、
残部がマグネシウムと不可避の不純物からなることを特徴とする耐熱・耐摩耗性マグネシウム合金。0.1% by weight of the following components <rare earth element ≦ 4% by weight
0.7 wt% <silicon ≤ 5 wt%
0.6% by weight <zinc ≤ 4% by weight
And 0 <manganese ≦ 1% by weight
0 <zirconium ≦ 1% by weight
0 <calcium ≦ 4.0% by weight
0 <aluminum ≦ 10% by weight
0 <silver ≦ 5% by weight
And at least one element selected from the group consisting of the following conditions: (calcium + rare earth element) / (aluminum + zinc)> 0.7
Satisfy,
A heat-resistant and wear-resistant magnesium alloy characterized in that the balance consists of magnesium and inevitable impurities.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP13487396A JP3865430B2 (en) | 1996-05-29 | 1996-05-29 | Heat and wear resistant magnesium alloy |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP13487396A JP3865430B2 (en) | 1996-05-29 | 1996-05-29 | Heat and wear resistant magnesium alloy |
Publications (2)
Publication Number | Publication Date |
---|---|
JPH09316586A JPH09316586A (en) | 1997-12-09 |
JP3865430B2 true JP3865430B2 (en) | 2007-01-10 |
Family
ID=15138484
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JP13487396A Expired - Fee Related JP3865430B2 (en) | 1996-05-29 | 1996-05-29 | Heat and wear resistant magnesium alloy |
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Families Citing this family (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2000104136A (en) * | 1998-07-31 | 2000-04-11 | Toyota Central Res & Dev Lab Inc | Magnesium alloy having fine crystal grain and its production |
DE19915277A1 (en) * | 1999-04-03 | 2000-10-05 | Volkswagen Ag | Magnesium alloy used e.g. in the manufacture of a wheel rim contains traces of cadmium, copper, iron, nickel and lanthanum and yttrium |
JP2001059125A (en) * | 1999-06-17 | 2001-03-06 | Toyota Central Res & Dev Lab Inc | Heat resistant magnesium alloy |
JP2001300643A (en) * | 2000-04-21 | 2001-10-30 | Mitsui Mining & Smelting Co Ltd | Manufacturing method of magnesium product |
US7029626B2 (en) * | 2003-11-25 | 2006-04-18 | Daimlerchrysler Corporation | Creep resistant magnesium alloy |
JP4700488B2 (en) * | 2005-12-26 | 2011-06-15 | 本田技研工業株式会社 | Heat-resistant magnesium alloy |
JP6814446B2 (en) * | 2019-03-12 | 2021-01-20 | 本田技研工業株式会社 | Flame-retardant magnesium alloy and its manufacturing method |
-
1996
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