The kinetics of solidification of Al-Si eutectic alloys under high pressure

Abstract

The kinetics of crystallization of eutectic alloys Al_100-xSi_x (χ=12, 18, 26 at.%) was investigated under pressures p=0.5, 2.5, 4.5 GPa. The values of supercooling and average grain size of silicon crystals were determined for alloys quenched from melt under different pressures with the cooling rate 10³ K/s. The data obtained were used to evaluate quantitatively the pressure dependences of surface tension (between melt and crystal) and activation energy of crystal growth which, in turn, have made it possible to determine the relative change of nucleation frequency and of the rate of crystal growth with pressure.

The possibility is shown, based on the investigation of mechanical properties of the samples obtained under high pressure, for improving the strength and the plasticity of A1-Si alloys by means of high pressure-high temperature treatment.

Key Words:

• Eutectic alloys
• solidification
• high pressure
• grain size
• undercooling
• mechanical properties.