Microstructural and mechanical properties of a new Er-modified cast and homogenized AlSiCuMg alloys

Abstract

The effect of the addition of 0.3 % Er on the microstructure and the mechanical properties of the cast Al–10Si–1.1Cu–0.7Mg-0.3Zr alloy have been investigated after the solid solution at 530 °C then quenching and aging with different temperatures and times. The findings demonstrated that the microstructure was refined, and novel intermetallic phases were formed due to the addition of Er. The presence of Erbium additives slightly modifies and increases the uniformity of the dendritic grain structure of the cast alloy. The formed phase particles, during solidification, do not change their morphology or dissolve upon homogenization. The new intermetallic phase strengthened the alloy, which was stable at high temperatures. The addition of 0.5 wt% Er enhanced the alloy's tensile strength and yield strength by 10 % and 5 %, respectively. Er also significantly improves its thermal conductivity. In addition, the modified alloy demonstrated a rapture. ${\sigma }_{100}^{250}$ equal 94 MPa, which indicates the high thermal stability of this alloy. According to the findings, Er is a potential alloying element that could enhance the functionality of piston alloys made of Al, Si, Cu, and Mg. The effect of adding 0.3 % erbium (Er) to an Al-Si-Cu-Mg alloy refines the microstructure, forms new intermetallic phases, increases strength and thermal conductivity, and improves creep resistance compared to a reference Al-Si alloy. The Er-modified alloy exhibits superior hardness compared to similar Al-Si-Cu-Mg alloys, exceeding the peak hardness of a reference alloy aged at 170 °C by 15 HV.