Electromagnetic construction and mechanical properties of in-situ Si reinforced Al matrix functionally graded material with Si-rich◎Si-poor coating structure. (1st December 2021) - Zou, Qingchuan
Abstract: How to break through the serious effect of hard and coarse primary Si on the properties of alloy matrix has become a major challenge for motivating the application of high-Si Al alloy piston in automobile lightweight. Herein, we proposed a novel in-situ Si reinforced Al-matrix functionally graded material with Si-rich◎Si-poor coating structure (Si-rich◎Si-poor FGM) by controlling the graded distribution of primary Si under rotating magnetic field. The results show that the segregation behaviors of primary Si and intermetallics (Mg2 Si, Al9 FeNi, Al7 Cu4 Ni) were directionally controlled during solidification of the multi-component Al–20Si alloy under electromagnetic stirring. The Si-rich◎Si-poor FGM has successfully combined the high tensile strength (296 MPa for Si-poor region) while meeting the gradient design of the mechanical properties (Vickers/Brinell hardness of Si-rich layer was 527%/86% higher than that of Si-poor region). The Si-rich◎Si-poor FGM shows the superior wear resistance when the temperature is less than 300 °C, which meets the limited operating temperature of automotive engine piston. More importantly, the Si-rich◎Si-poor FGM can be further fabricated into complex parts and constructed continuously, which give rise to the large-scale production of high-Si Al alloy piston in automobile lightweight.