Cr和Mn元素掺杂对高Nb-TiAl合金组织转变及拉伸性能的影响  

Effect of Cr and Mn Addition on Microstructure Evolution and Tensile Properties of High Nb-TiAl Alloy

作　　者：杨亮[1] 辛景景 张有为[2] 包春玲[2] 张来启[1] 林均品[1] 

机构地区：[1]北京科技大学新金属材料国家重点实验室,北京100083 [2]沈阳铸造研究所,辽宁沈阳110021

出　　处：《稀有金属材料与工程》2017年第10期3005-3010,共6页Rare Metal Materials and Engineering

基　　金：国家重点基础研究发展计划("973"计划)(2011CB605501);国家自然科学基金(51271016)

摘　　要：研究了β稳定元素Cr和Mn的掺杂对高Nb-TiAl合金的组织、相组成、凝固路径及室温、高温拉伸性能的影响。结果表明,Ti-45Al-8Nb-0.4B(at%,下同)合金中分别加入2Cr、2Mn或1Cr1Mn后,铸态组织中B2相逐步增加,而α_2相逐步减少。1Cr1Mn合金转变为由γ+B2两相组成的新型β-γ高Nb-TiAl合金。凝固路径由L→β→β+α→α+γ+β→α_2+γ+B2转变为L→β→β+γ→B2+γ。Cr和Mn的同时添加具有更明显的β相稳定作用。室温拉伸结果表明,随着B2相含量的增加,合金的强度与延伸率均降低。而在900℃条件下,合金延伸率出现先降低后升高的现象。这说明,高温下合金中β相含量达到一定程度时(本研究为14.4%),有利于协调变形。The variation of microstructure evolution, phase composition, solidification path and tensile properties of high Nb-TiAl alloys alloyed with β stable elements Cr or/and Mn were studied. The results show that volume fraction of B2 phase gradually increases while α_2 phase gradually decreases in as-cast microstructures of Ti-45 Al-8 Nb-0.4 B（atom fraction, %, similarly hereinafter） alloyed by 2 Cr, 2 Mn and 1 Cr1 Mn. 1 Cr1 Mn alloy turns into the novel β-γ high Nb-TiAl alloy, which is composed of γ and B2 two phases rather than γ, α_2 and B2 three phases. The solidification path changes fromL→β→β＋α→α＋γ＋β→α_2＋γ＋B2 to L→β→β＋γ→B2＋γ. The co-addition of Cr and Mn has more obvious β stable ability. The room temperature tensile results reveal that with the increase of B2 phase, the strength and elongation both decrease. While the elongation decreases firstly and increases subsequently at 900 °C. This phenomenon indicates that when the β phase content reaches a certain level, which is 14.4% in this study, β phase is advantageous to deformation at high temperature.

关 键 词：β凝固 β-γ高Nb-TiAl合金 组织转变 拉伸性能 Cr和Mn 

分 类 号：TG146.23[一般工业技术—材料科学与工程]