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以新型Co基合金Co-9Al-9W-2Ta-0.02B成分为基础,分别添加了原子分数为2%、4%、6%、9%的Mo元素替代W(分别称2Mo、4Mo、6Mo、9Mo合金,W+Mo的原子分数为9%,无Mo添加的称为0Mo合金),研究了Mo元素对合金相组成、显微组织形貌、维氏硬度和高低温压缩强度的影响。结果表明铸态合金由Co的固溶体γ相和Co3(Al,Me)金属间化合物γ′相组成(其中Me为合金元素W、Mo、Ta),γ相是基体,γ′相位于γ相界。1 350℃/8h固溶+800℃/100h时效处理后0Mo、2Mo和4Mo合金的γ相中均匀析出了与之共格的立方形γ′相Co3(Al,Me),尺寸为200～300nm,原铸态的γ′相消失;6Mo和9Mo合金的组织与0Mo、2Mo和4Mo合金完全不同,γ相基体析出大量针状TCP相,原γ相晶界处的γ′相中的W和/或Ta扩散离开而变成了Co3(Al,Mo)相,但基本保持铸态特征。各合金均出现反常屈服现象,随着Mo原子分数的提高,热处理合金室温和高温强度均有所降低,且反常屈服温度向低温方向移动。
Based on the new Co-9Al-9W-2Ta-0.02B composition, Mo elements with atomic fractions of 2%, 4%, 6% and 9% were added instead of W (2Mo, 9Mo alloy, the atomic fraction of W + Mo is 9% and the Mo-free alloy is 0Mo). The effects of Mo on the phase composition, microstructure, Vickers hardness and high and low temperature compressive strength of the alloy were studied. The results show that the as-cast alloy consists of solid solution phase of Co and γ phase of Co3 (Al, Me) intermetallic compound (where Me is the alloying element of W, Mo, Ta) . The cubic γ ’phase Co3 (Al, Me) precipitates uniformly in the γ phase of 0Mo, 2Mo and 4Mo alloys at 350 ℃ for 8 h and 800 ℃ for 100 h. , The as-cast γ ’phase disappears. The microstructures of 6Mo and 9Mo alloys are completely different from that of 0Mo, 2Mo and 4Mo alloys. A large number of needle-like TCP phases are precipitated in the γ phase matrix, and W in the γ’ / Or Ta diffused away to become a Co3 (Al, Mo) phase, but retained the as-cast features. All alloys showed abnormal yield phenomenon. With the increase of Mo atomic fraction, the room temperature and high temperature strength of heat treatment alloy decreased, and the abnormal yield temperature shifted to the low temperature.