Temperature dependent age hardening behaviour of 6061–SiCp composite

Abstract

In this research the age hardening behaviour of 6061–15 wt-%SiCp composite was investigated at different temperatures. The greatest age hardening effect with highest peak aged hardness (110 HV) was obtained at an intermediate temperature (175°C) with 2 h holding. This was attributed to the presence of the transition precipitate of smallest size (18 nm) occupying a reasonable volume fraction. The precipitation occurred at the preferred sites of dislocation through short circuit diffusion. Accordingly, the activation energy of the age hardening process exhibited much lower value (26 kJ mol⁻¹) than that of volume diffusion (124–130 kJ mol⁻¹). Dislocation annihilation was observed during the course of precipitation and precipitate coarsening process.

Keywords:

• 6061–SiCp composite
• Aging temperature
• Precipitation
• Dislocation
• Diffusion
• Electron microscopy