Transactions of Nonferrous Metals Society of China The Chinese Journal of Nonferrous Metals

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中国有色金属学报

ZHONGGUO YOUSEJINSHU XUEBAO

第14卷    第12期    总第69期    2004年12月

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文章编号: 1004-0609(2004)12-2003-06
Al3Ti3B中间合金对AZ91D镁合金组织及
力学性能的影响
龚丽勤1,李建国1,周   鹏1,王发奇2,仝仲盛2,陶占东2

( 1. 清华大学 材料科学与工程系,北京 100084;
2. 北京广灵精华科技有限公司,北京 100072
)

摘 要: 研究了Al3Ti3B中间合金对AZ91D镁合金显微组织及力学性能的影响。通过光学显微镜和扫描电子显微镜观察发现,Al3Ti3B中间合金能显著减小AZ91D合金的二次枝晶臂间距与晶粒尺寸,在加入0.3%Al3Ti3B时晶粒尺寸就由原来的约260 μm减小至约100 μm。伴随着合金晶粒尺寸的减小,合金的抗拉强度、屈服强度和延伸率都明显提高,这主要是由于晶粒细化后能阻碍裂纹扩展的有效晶界增多,晶界强化作用显著;同时,Al3Ti3B中间合金的加入促使溶质均匀分布,使共晶体(α+Mg17Al12)形貌发生改变,共晶体尺寸减小,这有利于裂纹切过脆性的共晶体传播,提高合金的变形协调能力。

 

关键字: 镁合金;Al3Ti3B;晶粒细化;二次枝晶臂间距;共晶体;力学性能

Effect of Al3Ti3B master alloy on microstructure and mechanical properties of AZ91D magnesium alloy
GONG Li-qin1, LI Jian-guo1, ZHOU Peng1, WANG Fa-qi2
TONG Zhong-sheng2, TAO Zhan-dong2

1. Department of Materials Science and Engineering,
Tsinghua University, Beijing 100084, China; 
2. Guangling Magnesium Science and Technology Co. Ltd,
Beijing 100072, China

Abstract: The influence of Al3Ti3B master alloy on the microstructure and mechanical properties of AZ91D magnesium alloy was investigated. Apparent grain refinement and decrement of the secondary dendrite arm space were found in the castings treated with Al3Ti3B by optical microscope and scanning electron microscope, and the grain size decreased from 260 μm to 100 μm merely with 0.3% addition. With the decreasing of secondary dendrite arm space or grain size, the ultimate tensile strength, yield strength and elongation are increased in the as-cast alloys. It can be explained that the density of grain boundaries becomes higher, which act as obstacles to the crack propagation with a smaller grain size; the addition of Al3Ti3B alloy leads to the homogeneous distribution of solute, and refines the eutectic Mg17Al12 phase, improves the deformability. 

 

Key words: magnesium alloy; Al3Ti3B; grain refinement; secondary dendrite arm space; eutectic; mechanical property

ISSN 1004-0609
CN 43-1238/TG
CODEN: ZYJXFK

ISSN 1003-6326
CN 43-1239/TG
CODEN: TNMCEW

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