Microstructure evolution and mechanical properties at high temperature of selective laser melted AlSi10Mg

In this study, the microstructure and tensile properties of selective laser melted AlSi10Mg at elevated temperature were investigated with focus on the interfacial region. In-situ SEM and in-situ EBSD analysis were proposed to characterize the microstructural evolution with temperature. The as-fabricated AlSi10Mg sample presents high tensile strength with the ultimate tensile strength (UTS) of similar to 450 MPa and yield strength (YS) of similar to 300 MPa, which results from the mixed strengthening mechanism among grain boundary, solid solution, dislocation and Orowan looping mechanism. When holding at the temperature below 200 degrees C for 30 min, the microstructure presents little change, and only a slight decrement of yield strength appears due to the relief of the residual stress. However, when the holding temperature further increases to 300 degrees C and 400 degrees C, the coarsening and precipitation of Si particles in alpha-Al matrix occur obviously, which leads to an obvious decrease of solid solution strength. At the same time, matrix softening and the weakness of dislocation strengthening also play important roles. When the holding temperature reaches to 400 degrees C, the yield strength decreases significantly to about 25 MPa which is very similar to the as-cast Al alloy. This might be concluded that the YS is dominated by the matrix materials. Because the softening mechanism counteracts work hardening, the extremely high elongation occurs. (C) 2020 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Automated summary

This study investigated the microstructure and tensile properties of selective laser melted AlSi10Mg at elevated temperature, revealing a significant decrease in tensile strength and increase in elongation when the holding temperature reaches 400 degrees Celsius.