Effect of heat treatment on thermophysical properties of laser powder bed fusion formed AlSi10Mg alloy

Abstract

The AlSi10Mg alloy samples were successfully prepared by laser powder bed fusion（LPBF）. The effects of three kinds of heat treatment process，namely 130 ℃/4 h aging treatment，236 ℃/10 h annealing treatment，and 540 ℃/1 h solid solution treatment on the microstructure of the AlSi10Mg samples were investigated. After heat treatment，the evolution of coefficient of thermal expansion（CTE） and thermal conductivity of the AlSi10Mg alloy in the temperature range from room temperature to 400 ℃ was examined. The results show that spherical Si particles are precipitated within the aluminum matrix，while the complete network-like eutectic silicon structure is retained after aging treatment. After annealing，the network-like silicon structure is disappeared completely，and spherical Si particles are uniformly distributed within the matrix. After solution treatment，large blocky Si particles with the sizes from 1 μm to 3 μm appear. The thermal properties of the AlSi10Mg alloy have been improved significantly after heat treatment compared to the as-printed state. In particular，the CTE of alloy subjected to annealing is 1.64×10−5 ℃−1 to 2.1×10−5 ℃−1 within the temperature range from room temperature to 400 ℃，the average thermal conductivity is 179.6 W·m−1·K−1，the performance is superior to ageing and solution treatments.

Keywords

• alsi10mg
• laser powder bed fusion
• heat treatment
• microstructure
• thermophysical property