Effect of energy density on formability, microstructure and micro-hardness of selective laser melted Sc- and Zr- modified 7075 aluminum alloy

摘要

The effect of energy density on formability, microstructure and micro-hardness of Sc- and Zr-modified 7075 aluminum alloy fabricated by selective laser melting (SLM) has been studied. It was observed that, with the increase of energy density, the density of block specimen increased firstly and then remained unchanged. When the energy density is 375 J/mm(3), the roughness of surface decreased from 20.1 to 8.5. That's because the temperature of melt pool increased with the increase of energy input. What's more, the spreading and solute redistribution of melt pool were further improved. Due to heterogeneous nucleation mechanism of Al-3(Sc, Zr) particles, the grain refinement is obvious and the average grain size is 0.78 mu m at the energy density of 375 J/mm(3). With the combination effect of grain refinement and chemical composition, the micro-hardness increased firstly and then decreased with the increase of energy density. (C) 2019 Elsevier B.V. All rights reserved.