Ti6246钛合金β→α相变中晶界α相生长行为及其对微织构的影响  

Growth Behavior of Grain BoundaryαPhase and Its Effect on the Microtexture Duringβ→αPhase Transformation in Ti6246 Titanium Alloys

作　　者：齐敏 王倩 马英杰 曹贺萌[1,2] 黄森森 雷家峰[1,2] 杨锐 QI Min;WANG Qian;MA Yingjie;CAO Hemeng;HUANG Sensen;LEI Jiafeng;YANG Riu(School of Materials Science and Engineering,University of Science and Technology of China,Shenyang 110016,China;Shichangxu Innovation Center for Advanced Materials,Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China)

机构地区：[1]中国科学技术大学材料科学与工程学院,沈阳110016 [2]中国科学院金属研究所师昌绪先进材料创新中心,沈阳110016

出　　处：《金属学报》2025年第2期265-277,共13页Acta Metallurgica Sinica

基　　金：国家重点研发计划项目,No.2021YFC2801801;国家自然科学基金项目,No.51871225。

摘　　要：钛合金的初始α片层组织特征对其热机械加工过程中的显微组织演化及力学性能具有重要影响,掌握初始α片层组织演化规律是实现钛合金微观组织和力学性能精准调控的前提条件。本工作通过中断炉冷热处理方法研究了Ti6246钛合金β→α相转变过程中初始α片层组织的演变规律,分析了晶界α相(α_(GB))的生长行为及其对后续晶内α片层生长、微织构强度的影响。结果表明,钛合金由β单相区缓冷至α+β两相区的过程中,与两侧β晶粒都符合Burgers取向关系(BOR)的α_(GB)(2-BORα_(GB))优先在β晶界处形核。而后,与2-BORα_(GB)取向相近的晶内α片层在α_(GB)处形核并向两侧β晶粒内生长,2-BORα_(GB)与两侧α片层在晶界处形成较强的微织构。在α相生长早期,两侧β晶粒与2-BORα_(GB)的BOR偏差越小,较强的微织构形成越早。除2-BORα_(GB)优先发生β→α相转变外,与单侧β晶粒符合BOR的α_(GB)(1-BORα_(GB))也形核生长,但是,与1-BORα_(GB)取向相近的晶内α片层仅在符合BOR的单侧β晶粒内形成,而在另一侧β晶粒中则形成取向不同的晶内α片层,在晶界处形成较弱的微织构。The initial lamellar microstructure of titanium alloys significantly affects their microstructural evolution and mechanical property during thermo-mechanical treatments.Thus,the evolution of the initial lamellar microstructure must be explored to control the microstructure and enhance the mechanical property.The present work focuses on the evolution of the lamellar microstructure duringβ→αphase transformation via interrupted furnace cooling experiments to analyze the growth behavior of the grain boundaryαphase(α_(GB))and its effect on the subsequent growth of intragranularαlamellae and microtexture.Results show that when titanium alloy furnace cools from theβphase field to theα+βphase field,theα_(GB)holding Burgers orientation relationship(BOR)with both sides ofβgrains(2-BORα_(GB))has an advantage for early transformation at theβgrain boundary.In particular,type II(49.5°/<110>)and type III(60°/<110>)βgrain boundaries are preferential sites for the early nucleation ofα_(GB)particles.As the temperature decreases,αlamellae holding similar orientation to 2-BORα_(GB)grow to both sides ofβgrains.Thus,2-BORα_(GB)and both sides ofαlamellae form a strong microtexture at the grain boundary.At the early growth period of theαphase,the smaller theθ_(2-BOR)(misorientation of the close-orientedα_(GB)variant pair of parentsβ1 andβ2)of 2-BORα_(GB),the earlier the formation of a strong microtexture at the grain boundary.2-BORα_(GB)preferentially precipitates,whereas theα_(GB)holding BOR with only one side of theβgrain(1-BORα_(GB))nucleates.αlamellae holding a similar orientation to 1-BORα_(GB)grow to one side of the BOR-βgrain(holding BOR withα_(GB)),whereasαlamellae with a different orientation grow in the non-BOR-βgrain.Thus,1-BORα_(GB)and one side ofαlamellae form a weak microtexture at the grain boundary.

关 键 词：α+β钛合金 相变 择优生长 晶界α相 微织构 

分 类 号：TG146.2[一般工业技术—材料科学与工程]