Ti_(2)AlNb合金薄板热处理过程中O相析出行为  

Precipitation Behavior of O-Phase in Ti_(2)AlNb Alloy Sheets During Heat Treatment

作　　者：周亦奇 唐斌[1] 张智鑫[2,3] 邵启航 陈晓飞 ZHOU Yiqi;TANG Bin;ZAHNG Zhixin;SHAO Qihang;CHEN Xiaofei(State Key Laboratory of Solidification Processing,Northwestern Polytechnical University,Xi'an 710072,China;Baoti Group Co.,Ltd.,Baoji 721014,China;Xi'an Baoti New Material Technology Co.,Ltd.,Xi'an 710018,China)

机构地区：[1]西北工业大学凝固技术国家重点实验室,陕西西安710072 [2]宝钛集团有限公司,陕西宝鸡721014 [3]西安宝钛新材料科技有限公司,陕西西安710018

出　　处：《铸造技术》2025年第2期99-109,共11页Foundry Technology

基　　金：重庆市自然基金面上项目(CSTB2023NSCQ-MSX0824);重庆市技术创新与应用发展专项(CSTB2022TIAD-KPX0032)。

摘　　要：Ti_(2)AlNb合金可以长时间在650~750℃条件下工作,具有高比强度、良好的室温断裂韧性和良好的抗蠕变性等,被认为是最具应用潜力的高温轻质金属材料。为研究在不同热处理制度下O相形核和长大过程,探索显微组织演化规律和O相变体选择行为,采用包套轧制工艺作为加工方法,轧制材料名义成分为Ti-22Al-24Nb-0.5Mo(原子分数,%)。通过轧制得到厚度为1 mm的Ti_(2)AlNb合金板材。对轧制后板材进行固溶时效处理后,O相大量析出;随着时效温度的提高,O相板条越来越粗大,同时O相析出量先增加后减少,在930℃时O相析出体积分数达到最高,为52%。在该热处理制度下O相形核析出方式既有界面不稳定形核也有感生形核,但是O相在晶界附近的形核析出方式更多倾向于感生形核,界面不稳定形核得到的O相数量上较少。轧板在1000℃固溶、815℃时效以及920℃固溶、800℃时效这两种热处理之后,得到的组织均为双态组织,轧制后的固溶时效过程基本没有对O相变体的析出造成影响。Ti_(2)AlNb alloys can operate for extended periods at temperatures between 650 and 750℃,offering high specific strength,excellent room-temperature fracture toughness,and good creep resistance.These properties make Ti_(2)AlNb alloys one of the most promising lightweight metallic materials for high-temperature applications.The alloy sheets,with a final thickness of 1 mm,were produced via a clad rolling process,employing a nominal composition of Ti-22Al-24Nb-0.5Mo(at.%)as the rolling material.After the rolled sheets were subjected to solution aging treatment,a significant amount of O-phase precipitated.As the aging temperature increases,the O-phase lamellae grow coarser,and the amount of precipitated O-phase initially increases but then decreases.At 930℃,the volume fraction of the precipitated O-phase reaches its maximum value of 52%.Under this heat treatment regime,the nucleation mechanisms for O-phase precipitation include both interfacial instability nucleation and induced nucleation.However,near grain boundaries,the O-phase tends to nucleate and precipitate predominantly through induced nucleation,with fewer O-phase particles forming through interfacial instability nucleation.Following solution treatment at 1000℃and aging at 815℃,as well as solution treatment at 920℃and aging at 800℃,the resulting microstructures are bimodal.The solution aging process after rolling has little effect on the precipitation of O-phase variants.

关 键 词：Ti_(2)AlNb合金 包套轧制 微观组织 变体选择 

分 类 号：TG113.12[金属学及工艺—物理冶金]