摘要
研究了固溶处理对一种新型Ti-6Cr-5Mo-5V-4Al合金组织与室温拉伸性能的影响。研究发现：Ti-6Cr-5Mo-5V-4Al合金在α/β固溶处理后的典型组织为：变形拉长的β晶粒，晶粒破碎，原始β晶界处有项链状初生α相析出，经时效后，晶内则析出纵横交错的细小次生α相。β固溶处理后的典型组织为：等轴β晶粒，经时效后晶界处沿着一定取向析出次生α相薄片层，晶内弥散分布着平行交错的细小次生α相。随着固溶温度的升高，β晶粒尺寸逐渐增大，初生“相的含量逐渐减少，相转变温度以上固溶处理后初生“相完全消失。α/β固溶＋时效后显微组织中次生α相尺寸较小，大小均匀，长度在500nm左右；而β固溶＋时效后显微组织中次生α相尺寸较大，且大小不均，长度在200～1500nm左右。该合金经固溶处理后具有中等强度水平和良好的塑性，且在实验温度范围内，固溶温度越高，合金强度越低，塑性越好；经时效后，a／β固溶处理的时效强化效应明显强于β固溶处理后，强度差值达360MPa，主要是因为α/β固溶处理后初生α相的析出，导致残余β相更加稳定，时效时次生α相的驱动力小，以及残余大量的位错等缺陷为α相提供了较多的形核位置，因此次生α相尺寸细小且分布均匀弥散。
Effect of solution treatment on microstructures and tensile properties of a new type Ti-6Cr-SMo-5V：4Al alloy was studied. The experimental results showed that, the microstructure feature of Ti-6Cr-SMo-SV-4A1 solution treated in α/β region was that elongated and broken β grains due to deformation, accompanied with a necklace-shaped primary α phase at the priorβ grain boundary, and consequently after aging, showing a fine, intragranular secondary α phase with acicular shape. But the microstructure feature of the alloy solution treated in βregion was that coarsen equiaxial β grains due to recrystallization, subsequently aging showed α secondary α platelets along the preferred orientation at prior β grain boundary, and also intragranular secondary a phase with acicular shape but much thicker. With the solution temperature increased, β grain increased and volume fraction of primary α phase decreased and vanished finally when treatment at β phase region. Secondary α phase was quite fine and uniform with approximately 500 nm in length due to treated in α/β region plus aging, on the contrary, it was a little coarser and nonuniform with 200 -1500 nm in length due to treat- ment at β region plus aging. The treated alloy solution presented a moderate strength levels with a preferable ductility. With increasing the solution temperature, tensile strength decreased and ductility was optimized. And owing to subsequently aging treatment, aging hardening response of the alloy solution treated in α/β region was more preferable than treated in α region with a different of 300 MPa in strength, which mainly because secondary a phase was more finer and uniform when treated in α/β region plus aging, in this case, the remained β phase was more stable due to the precipitation of primary α phase.
出处
《稀有金属》
EI
CAS
CSCD
北大核心
2011年第5期639-643,共5页
Chinese Journal of Rare Metals
基金
国家科技支撑计划(2008BAE62B03)资助项目
关键词
亚稳Β钛合金
固溶处理
显微组织
拉伸性能
metastable β titanium alloy
solution treatment
microstructure
tensile properties
