Thermoelastic and texture behavior of aluminum at high pressure and high temperature investigated by in situ neutron diffraction

The behavior of aluminum under high pressures and temperatures was investigated by in situ time-of-flight neutron diffraction with a developed Toroidal Anvil Press (TAP-98). The effect of the displacement of the center of diffraction, which is caused by sample movement during compression, is corrected by an additional calibration. Unit-cell dimensions, measured up to P=5.7 GPa and T=900 K, were derived from the refinement results and fitted to the high-temperature Birch-Murnaghan equation of state. With (partial derivativeK(T)/partial derivativeP)(T) fixed at 4, we obtained K-0=72.8(+/-2.4) GPa, (partial derivativeK(T)/partial derivativeT)(P)=-0.04(+/-0.01) GPa K-1, and alpha(T) (K-1)=3.7(+/-1.6)x10(-5)+9.7(+/-3.5)x10(-8)T. Our data are compared with previous experimental data involving shock wave, static compression, ultrasonic, and thermal-expansion measurements and with theoretical predictions. The results demonstrate that the newly developed high-pressure high-temperature system for in situ neutron diffraction is reliable. It was also found that the crystalline orientation of Al grains became highly preferred when the sample was heated to 900 K at similar to4 GPa. (C) 2004 American Institute of Physics.