相变温度对钛及钛合金加工和热处理具有重要意义。采用计算法、差热分析法和连续升温金相法3种手段计算和测定了TC4两相钛合金(α+β)/β的相变温度。计算法由于各主要元素及杂质元素含量对相变温度的影响值是在一个含量范围内的计算值, 因此计算的相变温度与实测值是接近的; 差热分析法由于测量过程中加热产生相变滞后现象, 导致所测相变温度略高; 而连续升温金相法由于淬火温度间隔选择较小, 测量的准确性较高, 因此更能准确测量TC4钛合金的相变温度。通过连续升温金相法, 观察不同淬火温度的试样在光学显微镜下的显微组织变化, 发现升温过程中初生α相完全消失的温度, 从而确定了TC4钛合金的相变温度为998 ℃。并分析了不同钛合金相变温度差异的原因。

The phase transformation temperature was very important to titanium and titanium alloys. Three methods including the calculation method, differential scanning calorimetry and metallographic techniques were employed to calculate and measure the phase transformation temperature of TC4 titanium alloy. The comparison between the three methods indicated that the theory value obtained by the calculation method approaches the true value, because the method required that the content of each element in the TC4 alloy was in a certain range. The value obtained by the differential scanning calorimetry was a little exorbitant, because continuous heating delayed the phase transformation. The phase transformation temperature could be measured accurately by the metallographic technique if more quenching temperatures were chosen. In the metallographic method, the microstructure of samples quenched from different temperatures was observed and the temperature at which the primary α phase disappeared was determined, so that the transformation temperature of the TC4 titanium alloy was determined to be 998 ℃. The reason of the difference of phase transformation temperature between different titanium alloys was discussed.