梯度热处理快速优化Ti-6.8Mo-3.9Al-2.8Cr-2Nb-1.2V-1Zr-1Sn合金获得高强高韧性能的微观组织  

Achieving high strength and ductility in Ti-6.8Mo-3.9Al-2.8Cr-2Nb-1.2V-1Zr-1Sn alloy by rapid optimizing microstructure through gradient heat treatment

作　　者：汪畅 周薇 李斯韫 张晓泳 刘会群 WANG Chang;ZHOU Wei;LI Si-yun;ZHANG Xiao-yong;LIU Hui-qun(School of Materials Science and Engineering,Central South University,Changsha 410083,China;State Key Laboratory of Powder Metallurgy(Central South University),Changsha 410083,China)

机构地区：[1]School of Materials Science and Engineering,Central South University,Changsha 410083,China [2]State Key Laboratory of Powder Metallurgy(Central South University),Changsha 410083,China

出　　处：《Journal of Central South University》2023年第2期387-399,共13页中南大学学报（英文版）

基　　金：Project(2021YFB3700803) supported by the National Key Research and Development Program of China;Project supported by the State Key Laboratory of Powder Metallurgy (Central South University),China。

摘　　要：本研究采用高通量梯度热处理,建立了亚稳β钛合金Ti-6.8Mo-3.9Al-2.8Cr-2Nb-1.2V-1Zr-1Sn的微观组织与热处理之间的关系。首先,在梯度热处理炉中,对直径为10 mm、长度为92 mm的棒材进行746~909℃(β-转变温度(845±5)℃)的连续温度梯度固溶处理。然后,将梯度固溶后的样品切割成4个相同样品,其中3个样品分别在450℃、550℃和600℃下时效8 h。通过单个高通量样品的制备与表征,快速建立固溶温度对时效硬化行为的影响规律模型,并对梯度组织进行表征。结果表明:随固溶温度的升高,次生α相(αs)的宽度和间距减小,强度提高,伸长率降低,而随时效温度的升高,呈现相反的趋势;746°C固溶处理2 h后再在600°C时效8 h,获得了由初生α相(αp),亚微米级棒状α相(αr)和次生αs相组成的异构组织,具备很好强的韧性匹配,屈服强度和伸长率分别为1140 MPa和15%。In this study,a new high-throughput heat treatment method was applied to rapidly optimize the microstructure of metastableβtitanium alloy Ti-6.8Mo-3.9Al-2.8Cr-2Nb-1.2V-1Zr-1Sn to obtain high strength and ductility.Continuous temperature gradient solution treatment was created in a tubular furnace at 746−909℃(the β-transus temperature(845±5)℃)on a length rod.Then,the gradient soluted sample was cut into four identical ones,three of which were aged for 8 h at 450,550 and 600℃,respectively.The effect of solution temperature on age hardening was rapidly achieved,and the gradient microstructure was characterized in detail in one high-throughput sample.The results showed that,the width and spacing of secondaryαphase(αs)decreased with the increase of solution temperature,resulting in the increase of strength and the decrease of elongation,while with the increase of ageing temperature the opposite trend appeared.After solution treatment at 746℃ for 2 h and ageing at 600℃ for 8 h,the hierarchical microstructure composed of the primaryαphase(α_(p)),sub-microα-rods(α_(r)),andαs formed,which contributed superior combination between strength and ductility with the yield strength of 1140 MPa and elongation of 15%,respectively.

关 键 词：高通量 热处理 亚稳Β钛合金 异构组织 高强高韧 

分 类 号：TG156[金属学及工艺—热处理] TG146.23[金属学及工艺—金属学]