【作者】 董福宇；

【导师】 向青春；

【作者基本信息】 沈阳工业大学 ， 材料加工工程， 2009， 硕士

【摘要】 本文通过改变合金元素的加入量和熔体保温时间,研究了不同合金元素Sc、Zr、Ti对过共晶Al-Fe合金微观组织及力学性能的影响,重点研究了Sc、Zr、Ti在过共晶Al-5%Fe合金中的溶质分布规律。Sc、Zr、Ti合金化元素对初生Al₃Fe相的生长有重要的影响。在过共晶Al-5%Fe合金中加入微量Sc,在加入量为0.4%、保温时间为30min时效果较好,合金中的初生Al₃Fe相由粗大的针状基本转变为细小的针状、粒状和花朵状。合金的抗拉强度达到186.2MPa,提高了53.4%。Sc元素吸附在富Fe区周围,阻碍Fe原子迁移,增加界面前沿液相中Fe的浓度梯度,造成了成分过冷,使初生Al₃Fe相得到细化。在过共晶Al-5%Fe合金中加入微量Zr,在加入量为0.1%、保温时间为90min时效果较好,合金中的初生Al₃Fe相基本转变为花朵状和粒状。合金的抗拉强度达到177.9MPa,提高了46.5%。Zr在过共晶Al-5%Fe中一部分固溶于铝基体中,一部分固溶到Al₃Fe相中,通过原子占位抑制初生Al₃Fe相的择优生长,使之细化。微量元素Ti对过共晶Al-5%Fe合金的细化作用在加入量为0.3%、保温时间为30min时效果较好,初生Al₃Fe相变为短针状和花朵状,合金的抗拉强度达到146.6MPa,提高了20.8%。Sc、Zr复合对过共晶Al-5%Fe合金的细化作用在Sc、Zr加入量分别为0.3%和0.1%、熔体保温时间为30min时效果较好,初生Al₃Fe相转变为细小的针状,粒状和花朵状。合金的抗拉强度达到266.8MPa,提高了119.8%。Sc、Ti复合对过共晶Al-5%Fe合金的细化作用,在Sc、Ti加入量分别为0.25%和0.04%、熔体保温时间为30min时效果较好,初生Al₃Fe相转变为细小的针状和花朵状。合金的抗拉强度达到185.2MPa,提高了52.6%。Sc、Zr、Ti复合时,当添加量分别为0.4%Sc、0.2%Zr和0.2%Ti时初生Al₃Fe相主要以圆整的小颗粒状为主,同时还有少量的花朵状和细小的短针状初生Al₃Fe相存在。更多还原

【Abstract】 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.更多还原