摘要
对比研究了Ti-6Cr-5Mo-5V-4Al合金双时效和单时效对α相析出行为及力学性能的影响。组织观察显示,合金固溶淬火后得到等轴β晶粒。经过低温预时效后,在β晶内获得均匀弥散的α相团簇组织,但在β晶界出现无析出区(PFZ)。这种β晶内/晶界分区析出特征直接影响后续高温时效形貌。双时效后,在β晶内析出细小均匀的α相,但在β晶界,α相呈粗大片状。与之相比,单时效后,α相分布较为均匀,都为粗大层片。拉伸结果表明,与单时效试样相比,双时效试样抗拉强度高达约1630 MPa,但延伸率较差(约2%)。这种高强度归结为组织中亚微米、纳米量级α粒子强烈的析出强化效应,而急剧的延性损失主要源于β晶界处粗大α片诱发的形变局域化进而导致早期沿晶脆性断裂。
Precipitation behavior ofα-phase and its influence on mechanical properties have been investigated in Ti-6 Cr-5 Mo-5 V-4 Al metastableβ-Ti alloy by comparing the double aging and the single aging.The microstructural characterization shows that the quenched sample consists of equiaxedβ-grains.After the following low-temperature pre-aging,dense clusters composed of numerousαnano-laths evenly distribute insideβ-grain interiors,while there are precipitate free zones(PFZ)aroundβgrain boundaries.This precipitation feature betweenβ-grain interiors and their grain boundaries is inherited into the later high-temperature aged samples.It can be seen that after the double aging,the fine equiaxedαprecipitates homogeneously distribute inβ-grain interiors but theα-phase exhibits a coarse plate shape adjacent toβ-grain boundaries.On the contrary,theα-plates distribute much more evenly in the single-aged microstructure although the plates have larger dimensions.Tensile testing shows that the ultimate tensile strength of the double aging sample can be tuned up to^1630 MPa but accompanied by the degradation of ductility(~2%).The ultra-strength originates from the significant precipitation-strengthening effect as a result of the precipitation ofα-particles at the submicron-and nano-scales,and the loss of ductility can be attributed to the premature intergranular fracture caused by deformation localization alongβ-grain boundaries。
作者
查友
陈威
赵高峰
王悦
孙巧艳
肖林
孙军
Zha You;Chen Wei;Zhao Gaofeng;Wang Yue;Sun Qiaoyan;Xiao Lin;Sun Jun(State Key Laboratory for Mechanical Behavior of Materials,Xi'an Jiaotong University,Xi'an 710049,China)
出处
《稀有金属材料与工程》
SCIE
EI
CAS
CSCD
北大核心
2020年第6期2046-2053,共8页
Rare Metal Materials and Engineering
基金
国家自然科学基金(51301127,51871176)
陕西省自然科学基金(2018JM5098)。
关键词
钛合金
热处理
微观组织
力学性能
titanium alloys
heat treatment
microstructures
mechanical properties
