摘要
采用高精度差分膨胀仪DIL805A/D测试了BT25钛合金在不同加热速度下的线膨胀曲线,并获得了合金在相应加热速度下的β相变温度。为了验证膨胀法得到的BT25钛合金β相变温度的准确性,用金相显微镜和定量分析软件分析了β相变温度附近不同温度保温后冷却得到的金相组织中相的相对含量和组织演变规律。根据膨胀曲线分析了BT25合金在加热过程中,不同温度范围内的相变情况。最后,采用杠杆定律得到不同加热过程中BT25合金α→β相变时α相转变体积分数与温度之间的变化关系。研究结果表明:膨胀法能够准确测定不同加热速度下钛合金的α→β相变点;随着加热速度的增加,BT25钛合金α→β相变的起始温度和结束温度都升高,相变温度区间变窄,相变速率明显增大。相变速率峰值和出现峰值的温度随着加热速度的增加也增大;利用Kissinger方程计算得出了加热过程中BT25钛合金α→β相变激活能为953.15 k J·mol^(-1)。
Dilatometric curves of BT25 titanium alloy under different heating rates were measured by high differential dilatometry DILS05A/D, and β phase transition temperatures of alloy at corresponding heating rates were obtained. In order to validate the accuracy of these β phase transition temperatures, the relative content of phase and the evolution of microstructure which were acquired by cooling after tempering near the β phase transition temperature were analyzed by metallographic microscope and quantitative analysis software. Phase transformation at different temperature ranges during heating was analyzed on the basis of dilatometric curve. Finally, α phase transformation fraction as a function of temperature during different heating processes was obtained by lever rule. The results showed that the expansion method was able to measure accurately the β transformation temperature of BT25 titanium alloy at different heating rates. With the increase of heating rate, the starting and the finishing points of α→β phase transformation increased while the transformation range narrowed and the transformation rate increased. Meanwhile, the peak of transformation rate and the peak tempera- ture were becoming higher with the increase of heating rate. The overall activation energy for the α→β phase transformation in BT25 al- loy was evaluated on the basis of Kissinger equation, and the value was 953.15 kJ.mol^-1.
出处
《稀有金属》
EI
CAS
CSCD
北大核心
2016年第1期8-13,共6页
Chinese Journal of Rare Metals
基金
贵州省科技厅工业攻关项目(GY(2012)3002)
贵阳市科技局工业攻关项目([2012101]2-8)资助
关键词
BT25钛合金
加热速度
相变
激活能
BT25 titanium alloy
heating rate
phase transformation
activation energy
