Ti6Al4V合金相变及吸氢热力学研究

Phase Transformations and Thermodynamics Analysis of Hydrogen Absorption of Ti6Al4V Alloy

在823~1023 K的氢化温度范围内对Ti6Al4V合金进行了压力-成分等温线测试,研究了Ti6Al4V合金的相变和吸氢热力学。结果表明,当Ti6Al4V合金在不同的氢化温度下进行置氢处理时,氢压随着氢含量的增加而逐渐升高。由于Ti6Al4V合金中原始β相的存在,在置氢处理过程中,每个压力-成分等温线只有一个倾斜的压力平台。根据Vant's Hoff定律,压力平台区的焓变值和熵变值分别为-50.7±0.26 kJ/mol和-138.4±0.69 J·K^(-1)·mol^(-1)。随着置氢温度的升高,Sieverts常数呈先增大后逐渐减小的趋势。分析了Ti6Al4V合金在置氢处理过程中的相组成和相变。

Thermodynamics of hydrogen absorption and phase transformations in Ti6Al4V alloy were investigated by pressurecomposition(P-C) isotherm measurement at hydrogenation temperatures in the range of 823~1023 K. Results show that the hydrogen pressure is increased with increasing the hydrogen content when Ti6Al4V alloy is hydrogenated at different temperatures. Only one sloped pressure plateau occurs in each P-C isotherm during the hydrogenation treatment because of the existence of original β phase in Ti6Al4V alloy. According to Vant’s Hoff law, the values of enthalpy and entropy of the pressure plateau region are-50.7±0.26 kJ/mol and-138.4±0.69 J·K^(-1)·mol^(-1), respectively. The Sieverts constant increases firstly and then decreases gradually with increasing the hydrogenation temperature. The phase composition and phase transformation of Ti6Al4V alloy during the hydrogenation treatment were analyzed.