Precise Measurements of Lattice Compression of Al, Si and Al-Si Alloys by High Pressure X-Ray Diffractometry

Abstract

By making use of a cubic anvil press equipped with a rotating-target type X-ray generator and a goniometer, lattice compression in Al, Si and Al–Si alloys was precisely measured up to 90 kbar. The experimental precision was greatly improved by newly-devised treatments such as correctioning for off-centering of a sample and for peak shifts due to stacking faults, and the adoption of an extrapolation method and a hydrostatic pressure medium. The accuracy as high as ±0.02% in the lattice constant measurement was attained. It was found that the lattice compression in Si under hydrostatic pressure was appreciably inconsistent either with the lattice compression in a solid pressure medium or bulk compression previously measured by Bridgman.