Tensile and creep properties of Al–7Si–0.3Mg alloy with Zr and Er addition

The combined and singular effects of Zr and Er addition on the microstructure, tensile and impression creep behaviour of the cast A356 alloy were investigated. The Zr and Er refined the α-Al dendrites and secondary dendrite arm spacing (SDAS) and modified the eutectic morphology. The simultaneous addition of Zr and Er exhibited the smallest α-Al dendrites and SDAS with a fibrous eutectic morphology, resulting in the highest yield (∼118 MPa) and tensile (∼190 MPa) strength, and the largest creep resistance. The stress exponent, and the activation energy, were within the range of 6.28–7.22 and between 121.6 and 148.2 kJ mol−1, respectively. The lattice self-diffusion climb-controlled creep was the dominant creep mechanism. The constitutive creep equation was developed for each alloy. © 2020 Institute of Materials, Minerals and Mining.