钛合金α+β/β转变温度测定的金相法与差热分析法对比研究

A Comparative Study of Differential Thermal Analysis Method and Metallographic Observation Method for the α+β/β Transformation Temperature of Titanium Alloys

以α型钛合金TA7、α＋β型两相钛合金TC4及近β型钛合金Ti-1023为例,对比研究了金相法和差热分析法测定钛合金α＋β/β相转变温度的一致性问题。结果表明：α型钛合金TA7发生相变时,DSC曲线上产生1个明显的吸热峰,其涉及的温度范围约60℃,当定义DSC曲线的一阶导数的峰值为相变温度时,所测得的相变温度与金相法的很接近;α＋β型两相钛合金TC4和近β型钛合金Ti-1023发生相变时,DSC曲线仅表现为基线偏移,涉及的温度范围10-15℃,由DSC曲线一阶导数峰值定义的相变温度与金相法符合得很好。

Differential scanning calorimetry （DSC） method and metallographic observation method have been adapted for the measurement of α＋β/β transformation temperatures of a titanium alloy TA7, α＋β titanium alloy TC4 and near β titanium alloy Ti-1023, and the coincidence has been discussed in the present paper. For the TA7 alloy, an obvious endothermic peak which covers a temperature range of about 60℃ occurred during α＋β/β transformation. The transformation temperature defined by the peak of first order derivative of the DSC curve was much near the temperature determined by the metallographic observation method. For the alloys TC4 and Ti-1023, on the other hand, only little baseline shifts which cover a temperature range of about 10-15℃ was observed during transformation. A better coincidence with the metallographic observation method was achieved for the alloys TC4 and Ti-1023 owing to the much narrow transformation temperature range.