Application of the New Alumina Travel Time Pressure Scale to Study the Elasticity of Materials at Simultaneous High Pressure and High Temperature

Recently, a new method has been developed for in-situ pressure (P) determination in multi-anvil apparatus within the framework of acoustoelasticity. The acoustic travel times of Al₂O₃ were calibrated against the NaCl pressure scale up to 15GPa, 1173K in conjunction with synchrotron X-radiation, thereby providing a convenient and reliable gauge for pressure determination at ambient and high temperatures (T). As indicated by recent experiments at room temperature, the pressures derived from this new method are in excellent agreement with those from the fix-point methods, and the resultant equations of state on several materials (e.g., coesite, tungsten, hafnium, etc.) revealed remarkable agreement with those from the previous compression studies under hydrostatic conditions. In this study, the new experimental capability has been extended to experiments at simultaneous high P-T and is illustrated by our recent ultrasonic measurements on body-centered-cubic-Fe₉₀Ni₁₀ up to 8GPa and 773K. The successful application of Al₂O₃ travel time pressure gauge to high T experiments is expected to open new opportunities for offline laboratory studies of solid and liquid materials under high P-T in multi-anvil apparatus.