Equation of state of additively manufactured Ti-6Al-4V quasi-hydrostatically compressed and decompressed in a DAC to ~55 GPa

Ti-6Al-4V is widely used in industrial applications due in part to its suppression of the brittle, ω phase to high pressures. This has led to extensive previous studies on Ti-6Al-4V using a variety of static and shock compression platforms. However, advanced (e.g. additive) manufacturing techniques are well-known to affect macroscopic material properties, leading to intensive efforts to study these materials at the meso- and micro-scale to inform “process-structure- properties-performance” design of high performance parts. To determine effects of additive manufacturing processes at the crystal lattice scale, we quasi-hydrostatically compressed an additively manufactured sample of Ti-6Al-4V to ~55 GPa at 300K in a diamond anvil cell using KCl as a pressure-transmitting medium. Platinum was used as a primary internal pressure standard. We found that the transition from the low pressure α phase to the higher pressure ω phase began at roughly 42 GPa and the two phases coexisted until nearly 54 GPa. This phase boundary is >10 GPa higher than the same transition reported in recent studies of commercial Ti-6Al-4V. Upon decompression, the α phase begins to recover at ~23 GPa and both α and ω phases are present at ~0 GPa indicating that significant hysteresis exists in the sample.