Effect of Er, Zr, V, Ti microalloying and muti-field coupling melt deep purification on the microstructure and mechanical properties of Al-12Si-4.5Cu-2Ni alloy

Abstract

In this study, the effects of Er, Zr, V and Ti microalloying and muti-field melt deep purification on the microstructure and mechanical properties of Al-12Si-4.5Cu-2Ni alloy were investigated. The phase diagram calculation and DSC curve showed that the second phases of microalloyed Al-12Si-4.5Cu-2Ni alloy was mainly AlCuNi phase, (Al, Si)₃(Zr, Ti, V)-D0₂₂/D0₂₃, Al₂Cu, Al₃(Zr, Er) and Al₂Si₂Sr. The solidus and liquidus temperatures were 518.1 °C and 597.4 °C, respectively. The addition of Er significantly refined the grains and formed L1₂-Al₃(Zr, Er) coherent with the α-Al matrix. Under the action of microalloying elements, the stacking fault energy of aluminum alloy was remarkably reduced, and extensive stacking faults appeared in the α-Al matrix and eutectic Si. Through the coupling degassing of Ar and ultrasonic field, the size and number of pores in the alloy ingot were not only reduced, but also the size of the second phase was refined and distributed more uniformly. The yield strength, ultimate tensile strength and elongation of the alloy after microalloying and multi-field coupling degassing reached 163.9 MPa, 300.2 MPa and 3.2 %, respectively. The second phase of microalloying Al-12Si-4.5Cu-2Ni alloy was systematically analyzed, which will provide a basis for the subsequent design of heat-resistant aluminum alloy and the formulation of subsequent heat treatment process parameters.