High pressure melting and equation of state of aluminium

Melting curve of aluminium has been determined up to 50 GPa in a diamond an vil cell with laser heating. Using wavelength independent emissivity very g ood agreement was found with previous melting study, theoretical calculatio ns and shockwave experiments. Analysis of the data using Lindemann and Simo n melting equations suggests that melting occurs close to, but not exactly at the same pressure as measured at the cold state. Grueneisen parameter ga mma scales with volume as gamma/gamma(0)=V/V-0, where gamma(0)=2.2+/-0.1, a value close to 2.14 from adiabatic decompression experiments. The melting curve, when transformed to normalized coordinates, verifies the prediction of work of Schlosser et al. [Phys. Rev. B, 40 (1989) 5929] for the linear r elationship between normalized melting temperature and normalized pressure. Fit of the combined data from melting, thermal expansion, room compression , and shockwave studies to the Mie-Grueneisen thermal equation of state giv es gamma(0)=2.42+/-0.02; Anderson's thermal pressure model yields -0.032+/- 0.001 and -0.001+/-0.001 GPa/K for the temperature derivative of isothermal bulk modulus at constant pressure and constant volume, respectively. (C) 2 000 Elsevier Science S.A. All rights reserved.