钛合金固体银致脆行为研究

采用慢应变速率试验（ＳＳＲＴ）法并结合断口分析，研究了ＴＣ１１、Ｔｉ－８１１和ＴＣ４三种钛合金的固体银致脆（ＳＳＩＥ）行为，同时对ＳＳＩＥ机制进行了分析。结果表明，在２．４×１０－６ｓ－１慢速率拉伸条件下，磁控溅射Ａｇ膜使ＴＣ１１在４５０℃以上呈现出较显著的ＳＳＩＥ敏感行为，其ＳＳＩＥ下限温度约为４００℃。三种钛合金与Ａｇ箔紧密机械接触，在５００℃时均显示很高的ＳＳＩＥ敏感性，敏感程度依ＴＣ１１、ＴＣ４、Ｔｉ－８１１顺序增大。钛合金ＳＳＩＥ敏感性取决于Ａｇ与钛合金表面结合紧密程度及Ａｇ沿钛合金晶界扩散速率、Ａｇ表面自扩散速率和钛合金表面氧化膜破裂速率的相对大小

SOLID-SILVER-INDUCED EMBRITTLEMENT OF TITANIUM ALLOYS

The solid-silver-induced embrittlement(SSIE)of the titanium alloys TC11(an alpha-beta alloy),Ti-811(an alpha alloy),and TC4(an alpha-beta alloy)has been studied using slow strain rate(tensile)tests(SSRTs).It is found that magnetron sputtered silver film severely embrittles TC11 alloy when tested at a strain rate of about 2.4×10 6 per sec (ε· 1)and temperatures above 450℃.The severity of embrittlement increases with increasing temperature.A onset temperature of about 400℃ exists for SSIE of TC11.The titanium alloys TC11,Ti-811 and TC4 in intimate contact with silver foil also manifests severe embrittlement when tested at ε· 1 and 500℃.The severity of embrittlement increases in the sequence of TC11,TC4,Ti-811 order.SEM analysis shows that (1)the fracture path is both intergranular and transgranular cleavage, (2) surface self-diffusion of silver is the limiting transport mechanism,and (3)crack propagation in SSIE is controlled by both surface self-diffusion of silver and cracking of oxide film at crack tip.