用团簇成分式方法对Fe-Cr-A1-Mo-Nb合金进行成分解析,并在此基础上确定了Fe-Cr-A1三元基础成分式Fe75A19.375Cr15.625(at.％),进而添加Mo、Nb、Ta和Zr元素替代部分Cr元素.采用真空电弧熔炼制备设计的母合金锭,然后进行1200℃/2 h固溶处理,进而在800℃进行多道次热轧成板,再进行800℃/24 h时效处理,最后在不同温度进行高温固溶处理,研究了微量元素添加对合金高温组织稳定性的影响.结果表明,对于800℃/24 h时效的Mo/Nb/Ta/Zr合金化样品,第二相(Laves相)粒子均弥散分布于铁素体基体中.1000℃/1 h再固溶处理,使系列合金中的第二相粒子发生回溶,至1200℃/1 h固溶后只含有Mo/Nb的合金中的第二相粒子已全部溶入到基体中,而在Ta和Zr微合金化的样品中仍有第二相粒子存在于基体的晶界处,有效抑制了基体晶粒在高温下异常长大,从而提高基体的组织稳定性和合金在高温下的力学性能.
The composition rule of the high-performance Fe-Cr-Al-Mo-Nb alloys was investigated in light of a cluster formula approach,and then a ternary cluster formula of Fe75A 9375Cr15.625 (at.％) was determined.Mo,Nb,Ta,and Zr were added into the alloy to partially substitute for partial Cr of Fe-Cr-Al-Mo-Nb alloys.Alloy ingots were prepared by vacuum arc melting,and then solution-treated at 1200℃ for 2h before hot-rolled at 800℃ into sheets.The alloy sheets samples were aged at 800℃ for 24 hrs,followed by re-solution treatments at 1000℃,1100℃ and 1200℃ for 1 h respectively.The microstructure and microstructural stability at high temperature of the alloy sheetssamples under various treatments were comparatively studied compared to study the HT microstructural stability of this series of alloys.The results show that the fine precipitates (Laves phase) distributed homogeneously in the ferritic matrix of the aged Mo/Nb/Ta/Zr alloy sheetsed samples.However,these particles begin to re-dissolve into the matrix after 1000℃/1 h solution treatment.Moreover,these particles disappeared in the Mo/Nb containing alloy after 1200℃/1 h solution,while Ta or Zr further minor-alloying could still ensure a certain amount of precipitates distributed on the grain boundaries,which effectively suppresses the abnormal growth of grains at high temperature.Therefore,the HT microstructural stability at high temperature and the resulted ant mechanical properties could be improved.
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