中文摘要：

为了了解V-5Cr-5Ti合金（质量分数）热加工过程的基本物理机制,在Gleeble-3800热物理模拟试验机上采用热压缩方法测量合金在1373~1673K范围内的热激活参数。结果表明：抛物线型本构方程的应力指数n和激活能Q分别为4.87和375.89kJ/mol。通过引入临界应力参数（σ_0）,计算得到的激活能Q为288.34 kJ/mol,这与合金的自扩散激活能（270~300kJ/mol）相近。重复应力松弛实验得到合金的物理激活体积V_p和应变速率敏感指数m分别为（120~700）b~3和0.075~0.122。上述激活参数表明：V-5Cr-5Ti合金在1373~1673K和0.001~1.0s~（-1）范围内的热压缩物理机制为克服林位错钉扎的位错攀移。

英文摘要：

In order to well understand the elementary mechanisms that govern the hot working process of a V？5Cr？5Ti alloy （mass fraction, %）, thermal activation parameters under compression were measured in a temperature range of 1373？1673 K by a Gleeble？3800 system. The results show that the stress exponentn is 4.87 and the activation energyQis 375.89 kJ/mol for the power law equation. The activation energy is determined as 288.34 kJ/mol, which is close to the self-diffusion energy of alloy （270？300 kJ/mol） by introducing a threshold stress（σ0） variable. The typical values of physical activation volume （Vp） and strain rate sensitivity （m） are measured as （120？700）b3 and 0.075？0.122, respectively, by the repeated stress relaxation tests. These activation parameters indicate that the rate controlling mechanism for V？5Cr？5Ti alloy compressed in ranges of 1373？1673 K and 0.001？1.0 s？1 is the dislocation climb by overcoming of forest dislocations.