The Effects Of Sc, Zr And Ti Combination Alloying On The Microstructure And Mechanical Properties Of Hypereutectic Al-Fe Alloy

By changing the contents of minor elements and the holding time of molten melts,the influences of trace elements Sc,Zr,Ti on the microstructure and mechanical properties of hypereutectic Al-Fe alloy were investigated in the paper.The regularities of solute redistribution of the trace elements in the hypereutectic Al-5%Fe alloy were studied.The alloying elements of Sc,Zr and Ti have important effects on the growth of primary Al₃Fe phase.In the hypereutectic Al-5%Fe alloy,the optimal refining effect was attained when 0.4%Sc was individually added and the melt was holding for 30 minutes. The primary Al₃Fe phase changed from the shape of coarse needles to fine needle-like, particle-like and flower-like.The tensile strength of the alloy approached to 186.2MPa, being raised 53.4%.The element Sc is rich in the Fe-rich area,disturbing the transportation of Fe atoms and increasing the concentration gradient of Fe on the solidification interface, thus promoting the constitutional supercooling and refining the primary Al₃Fe phase.In the hypereutectic Al-5%Fe alloy,the optimal refining effect was attained when 0.1%Zr was individually added and the melt was holding for 90 minutes.The primary Al₃Fe phase was fundamentally changed to be particle-like and flower-like.The tensile strength of the alloy was up to 177.9MPa,being raised 46.5%.Part of the Zr element is dissolved in the Al-matrix and the other is dissolved in the Al₃Fe phase.They suppress the preferential growth of Al₃Fe phase by means of atom occupying space.Therefore,the primary Al₃Fe phase is refined.In the hypereutectic Al-5%Fe alloy,the optimal refining effect was attained when 0.3%Ti was individually added and the melt was holding for 30 minutes. The primary Al₃Fe phase changed to be fine needle-like and flower-like.The tensile strength of the alloy approached to 146.6MPa,being raised 20.8%.In the hypereutectic Al-5%Fe alloy,the optimal refining effect was attained when 0.4%Sc and 0.1%Zr were added and the melt was holding for 30 minutes.The primary Al₃Fe phase changed to be fine needle-like,particle-like and flower-like.The tensile strength of the alloy approached to 266.8MPa,being raised 119.8%.In the hypereutectic Al-5%Fe alloy,the optimal refining effect was attained when 0.25%Sc and 0.04%Ti were added and the melt was holding for 30 minutes.The primary Al₃Fe phase changed to be fine needle-like,and flower-like.The tensile strength of the alloy approached to 185.2MPa, being raised 52.6%.When 0.4%Sc,0.2%Zr and 0.2%Ti were simultaneously added,the primary Al₃Fe phase was appeared mainly to be particle-like,and small amounts of Al₃Fe phase was fine needle-like and flower-like.