摘要
研究了两相区固溶温度及固溶后冷速对Ti-6Al-4V (TC4)合金元素再分配行为的影响,利用EPMA技术表征了初生α相(αp)以及β转变区域(βt)的元素浓度,考察了βt显微组织尺寸随固溶温度及元素浓度的变化。结果表明:随着固溶温度升高,βt区域元素浓度变化显著,表现为Al含量升高、V含量降低,而αp晶粒中元素浓度变化较小,导致两区域元素浓度差异减小;同一固溶温度下,以不同冷却方式(水冷、空冷及炉冷)冷却的显微组织及元素分布显示,冷却速率越低,αp比例越高,αp与βt之间元素浓度差异越明显。合金经固溶水冷、空冷后,βt分别为淬火马氏体、次生α相(αs)+残余β相,2种冷速下βt的显微组织尺寸均与高温β相内的元素浓度水平有关,即βt内部显微组织尺寸受固溶温度的显著影响。利用纳米压痕技术表征了不同固溶温度下微区域(αp、βt)的力学特征,结果表明,密排六方(hcp)晶格αp本身呈现的力学行为的各向异性对其纳米压痕性能起决定性作用,而β_t的弹性模量及硬度主要受αs片层尺寸的影响。最后讨论了"固溶温度-微区元素浓度-微区显微组织-微区力学性能"之间的关系。
During the thermal treatments of α+β titanium alloys in(α+β) phase field, alloying element partitioning effect takes place accompanying with the α?β transformation, which results in the segregation of α stabilizing elements(Al, O) and β stabilizing elements(V, Mo, etc.) into the corresponding phases respectively. The element partitioning effect will further affect the microstructure characteristics(phase constitution, microstructure size), plastic deformation modes and the final mechanical properties of the alloy. In this work, the influences of solution temperature and cooling rate on the element partitioning behavior during solution process of Ti-6 Al-4 V alloy in(α+β) phase field were investigated. The element concentrations in primary α phase(α_p) and β transformed region(β_t) were characterized by EPMA technique. The microstructural variation of βtwith respect to solution temperature was analyzed. It was found that βt showed an obvious increase of Al content and decrease of V content with the increasing of solution temperature, while the αpexhibited less noticeable change, which led to the reduction of concentration difference between the two phases. Under the same solution temperature, the microstructures and element distributions at different cooling rates(water quenching, air cooling, furnace cooling) were exhibited. The slow cooling processing especially furnace cooling would induce higher volume fraction of αpphase and more pronounced element partitioning. The microstructural characteristics of β_t cooled from different solution temperatures were further analyzed. During the water or air cooling process, the transformations of β→matensite/α_s happened, and the sizes of martensite or α_s were postulated to be dependent on the element concentration of β phase. The properties of local microstructure(α_p, β_t) were further measured by nanoindentation. It indicates that the intrinsically anisotropic character of the hexagonal crystal structure(hcp) of the α_p phase has decisive co
作者
黄森森
马英杰
张仕林
齐敏
雷家峰
宗亚平
杨锐
HUANG Sensen;MA Yingjie;ZHANG Shilin;QI Min;LEI Jiafeng;ZONG Yaping;YANG Rui(Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China;School of Materials Science and Engineering, Northeastern University, Shenyang 110819, China)
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2019年第6期741-750,共10页
Acta Metallurgica Sinica
基金
中国科学院B类先导专项项目No.XDB06050100
国家重点研发计划项目Nos.2016YFC0304201
2016YFC0304206
国家自然科学基金项目No.51871225~~
关键词
α+β钛合金
元素再分配
显微组织
纳米压痕
α+β titanium alloy
alloying element partitioning
microstructure
nanoindentation
