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23卷    第z1期    总第1期    2013年12月

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文章编号:1004-0609(2013)S1-0771-05
Al和B含量对高温TiAl合金室温力学性能的影响
张志勇,马 睿,徐向俊,张来启,林均品

(北京科技大学 新金属材料国家重点实验室,北京 100083)

摘 要: 采用磁感应悬浮熔炼法制备3个含有高含量合金元素(7Nb-2.5V-1.0Cr)的TiAl合金铸锭,Al和B的含量分别为46Al-0B、48Al-0B、46Al-0.7B。采用光学显微镜(OM)和扫描电子显微镜(SEM)观察了3种合金的铸态显微组织,采用电子拉伸材料试验机测试了合金室温力学性能并观察了断口形貌。结果表明:高含量合金元素的添加使发生包晶转变的临界Al含量增加到47%(摩尔分数)左右,发生包晶转变的48Al-0B合金组织较为粗大(大于 1 000 μm),Al含量的降低使铸态组织细化;3种合金中46Al-0B合金具有最优异的室温力学性能,抗拉强度640 MPa、屈服强度590 MPa、塑性伸长率0.42%;46Al-0.7B合金由于B的添加恶化了室温力学性能,抗拉强度375 MPa,且几乎为零塑性断裂,硼化物主要以弯曲带状大量分布在片层团界面和内部。

 

关键词: 高温TiAl合金;显微组织; 室温力学性能; 断口形貌;硼化物

Effects of Al and B contents on RT-mechanical properties of cast high temperature TiAl alloys
ZHANG Zhi-yong, MA Rui, XU Xiang-jun, ZHANG Lai-qi, LIN Jun-pin

State Key Laboratory of Advanced Metals and Materials,
University of Science and Technology Beijing, Beijing 100083, China

Abstract:TiAl Ingots containing high contents of alloy elements(7Nb-2.5V-1.0Cr) were prepared by magnetic levitation melting method, the Al and B contents were 46Al-0B, 48Al-0B, 46A-0.7B respectively (mole fraction, hereafter). The as-cast microstructures were examined by optical microscopy(OM) and scanning electron microscopy (SEM). Room- temperature mechanical properties were tested by electronic tensile testing machine, and fracture morphologies were studied by SEM. The results show that the critical aluminum content in which peritectic reaction happened increases to approximately 47% (mole fraction). Coarse grain size above 1 000 μm is obtained in petitectic alloy 48Al-0B, refined microstructure can be obtained by decreasing Al content. Room temperature tensile tests prove that alloy 46Al-0B has the best mechanical property. Tensile strength, yield strength, ductil elongation are 640 MPa, 590 MPa, 0.42%, respectively; Alloy 46Al-0.7B is refined dramatically by boron addition, but mechanical properties deteriorate, the tensile strength is 374 MPa, and nearly crack without ductil deformation. Borides distribute in or along the lamellar colonies with curved ribbon morphology.

 

Key words: high-temperature TiAl alloys; microstructure; RT mechanical properties; fracture morphologies; boride

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

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

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