We report results from a series of diamond-anvil-cell synchrotron x-ray diffraction and large-volume-press experiments, and calculations, to investigate the phase diagram of commercial polycrystalline high-strength Ti-6Al-4V alloy in pressure–temperature space. Up to ∼30GPa and 886K, Ti-6Al-4V is found to be stable in the hexagonal-close-packed, or α phase. The effect of temperature on the volume expansion and compressibility of α–Ti-6Al-4V is modest. The martensitic α → ω (hexagonal) transition occurs at ∼30GPa, with both phases coexisting until at ∼38–40GPa the transition to the ω phase is completed. Between 300K and 844K the α → ω transition appears to be independent of temperature. ω–Ti-6Al-4V is stable to ∼91GPa and 844K, the highest combined pressure and temperature reached in these experiments. Pressure–volume–temperature equations-of-state for the α and ω phases of Ti-6Al-4V are generated and found to be similar to pure Ti. A pronounced hysteresis is observed in the ω–Ti-6Al-4V on decompression, with the hexagonal structure reverting back to the α phase at pressures below ∼9GPa at room temperature, and at a higher pressure at elevated temperatures. Based on our data, we estimate the Ti-6Al-4V α–β–ω triple point to occur at ∼900K and 30GPa, in good agreement with our calculations.

我们报告了一系列金刚石-砧座同步加速器 X 射线衍射和大体积压力实验和计算的结果，以研究商业多晶高强度 Ti-6Al-4V 合金在压力-温度空间中的相图. 在高达 30GPa 和 886K 时，发现 Ti-6Al-4V 在六方密排或α相中是稳定的。温度对α -Ti-6Al-4V 的体积膨胀和可压缩性的影响不大。马氏体α → ω（六方）转变发生在~30GPa，两相共存，直到~38-40GPa完成向ω相的转变。在 300K 和 844K 之间，α → ω转变似乎与温度无关。ω -Ti-6Al-4V 在~91GPa 和 844K 是稳定的，这是这些实验中达到的最高压力和温度。生成了 Ti-6Al-4V 的α和ω相的压力-体积-温度状态方程，发现与纯 Ti 相似。在减压时在ω -Ti-6Al-4V中观察到明显的滞后现象，六方结构在室温下低于 9GPa 的压力下恢复到α相，而在高温下在更高的压力下。根据我们的数据，我们估计 Ti-6Al-4V α - β - ω三相点发生在~900K和30GPa，与我们的计算非常吻合。