Yixian Liu, Yixian Liu, Xiaole Cheng, Yongchang Liu, Yongchang Liu, Zunian He, Xiangyi Jiao, P. Wang, Zhengda Lu, Genglei He, Yicheng Zhang, Xueke Li, Shoumei Xiong
In this paper, we propose a microstructure optimization strategy involving matrix purification via element B, and refinement of eutectic cells by forming a bio-inspired core-shell structure via element Yb to achieve synergistic improvement in both thermal conductivity and strength of a high-pressure die-cast Al-1.5Fe-1Ni alloy. The die-cast Al-1.5Fe-1Ni-0.15Yb-0.03B alloy exhibits an ultra-high thermal conductivity exceeding 200 W·m -1 ·K -1 along with a yield strength of nearly 90 MPa. In the die-cast alloy, element B purifies the Al matrix by reacting with transition metal impurities to form (Al,M)B 2 borides (M=V, Cr, Mn, Zr, Ti), thereby reducing solute scattering and enhancing thermal conductivity. The fine borides also contribute to the precipitation strengthening. Meanwhile, element Yb promotes the precipitation of Al 3 Yb phases containing Si impurities which are purified from the Al matrix, and forms a bio-inspired core-shell structure around the Al 9 NiFe eutectics to refine the eutectic cells. The refinement and purification effects of Yb improve both thermal conductivity and strength of the die-cast alloy. This work offers a strategic reference for developing high-pressure die-cast aluminum alloys with ultra-high thermal conductivity.