Multiscale study of the microstructure and strengthening mechanism of an Al-Si-Fe alloys using synchrotron X-ray

This study combines synchrotron radiation X-ray computed tomography (SRXCT) and In-situ synchrotron radiation X-ray diffraction (SRXRD) to investigate the microstructure of an Al-Si-Fe alloy and to analyze the evolution of lattice strain and the load transfer effect during tensile process. The results show that the microstructure of the alloy is mainly composed of α-Al, eutectic Si phase and β-Al 5 FeSi phase. SRXCT reveals that the plate-like Fe-rich phases forming interconnected cross-structures. The thick Fe-rich phases and grain boundaries significantly reduce the thermal conductivity, whereas the fibrous eutectic Si phase and small pores have a minor influence. SRXRD shows that the bearing-stress of β-Al 5 FeSi phase continues to increase until failure. The β-Al 5 FeSi phase and eutectic Si exceed the bearing-stress of Al at failure. The tensile strength of the alloy is 154 MPa, the yield strength is 90 MPa and the elongation is 3.6 %. The thermal conductivity is 148 W/(m·k).