【作者】 王静媛；

【导师】 向青春；

【作者基本信息】 沈阳工业大学 ， 材料加工工程， 2007， 硕士

【摘要】 本文通过改变晶粒细化剂加入量和熔体保温时间研究了不同的晶粒细化剂（Al-Ti-B、Al-Ti-C、Al-Ti-C-B）、合金元素Sc以及合金元素与电流处理的联合作用对Al-5％Fe合金微观组织形态及力学性能的影响，并对其作用机理进行了探讨。在过共晶Al-5％Fe合金中加入Al-Ti-B中间合金细化剂，当加入量为1％、保温时间为90min时效果较好，Al-5％Fe合金中初生Al₃Fe相由未添加细化剂时的粗大板条状变为花朵状和颗粒状，并且尺寸明显减小。在过共晶Al-5％Fe合金中加入Al-Ti-C-B中间合金细化剂，在加入量为1％、保温时间为90min时效果较好，合金中初生Al₃Fe相主要变为尺寸较小的花朵状形貌，并且在其周围分布着部分颗粒状的Al₃Fe相，分布也相对较均匀。合金的抗拉强度由121.4MPa增加到131.0MPa，提高了7.9％。在过共晶Al-5％Fe合金中加入Al-5Ti-0.25C中间合金细化剂，当添加量为1％、保温时间为30min时达到最佳细化效果。合金中初生Al₃Fe相由原来粗大的针片状基本转变为细小的短棒状、花朵状和颗粒状。合金的抗拉强度为144.2MPa，提高了18.8％。在过共晶Al-5％Fe合金中加入微量合金元素Sc，在加入量为0.4％、保温时间为30min时效果最佳，合金中的初生Al₃Fe相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元素的加入既能造成界面前沿的成分过冷又能降低初生Al₃Fe相与基体间的错配度及界面能，从而对初生Al₃Fe相产生细化作用。过共晶Al-5％Fe合金在加入0.4％Sc的基础上进行电流密度为59A／dm²的电流处理，组织得到较为明显的细化，粒状的初生Al₃Fe相尺寸更加细小，短针状相减少，放射状的组织得到明显改善。Al-5％Fe合金在加入1％Al-5Ti-0.25C的基础上再进行电流密度为59A／dm²的电流处理，初生Al₃Fe相尺寸明显变小，主要为粒状和短针状，组织进一步细化。更多还原

【Abstract】 By changing the addition and holding time, the influences of different grain refiners （including Al-Ti-B, Al-Ti-C, Al-Ti-C-B）, trace element Sc, and combination of alloying elements with electric current treatment on the microstructure and mechanical property of hypereutectic Al-Fe alloy were investigated in this thesis. The mechanisms of these grain refiners on hypereutectic Al-Fe alloy were also discussed based on the experimental results.When 1％Al-Ti-B was added in the hypereutectic Al-5%Fe alloy, and the holding time of alloy melt was kept 90 min, the refining effect on the alloy was better. The primary Al₃Fe phase changed from the extremely thick plate-like to fine particle-like and flower-like, furthermore, the size of the primary Al₃Fe phase was reduced obviously.While 1％Al-Ti-C-B was added in the hypereutectic Al-5％Fe alloy, and the holding time of alloy melt was kept 90 min, the better refining effect was observed. The primary Al₃Fe phase majorly appeared fine flower-like, and some particle-like primary Al₃Fe phase was dispersed around it. The tensile strength of the alloy was raised to 131.0MPa from 121.4MPa, and was improved 7.9％.Further, Al-5Ti-0.25C was added in the hypereutectic Al-5％Fe alloy. When the addition was 1％and the holding time was kept 30min for the alloy melt, the best refining effect was achieved. The primary Al₃Fe phase changed from the extremely thick plate-like to fine needle-like, flower-like and particle-like. The tensile strength of the alloy was 144.2MPa, and was raised 18.8％.In addition, trace element Sc was added in the hypereutectic Al-5％Fe alloy. When 0.4％ Sc was added with the holding time of melt being 30 min, the best refining effect was acquired. The primary Al₃Fe phase was changed to fine needle-like, particle-like and flower-like. And the tensile strength of the alloy approached 186.2MPa, and was raised 53.4％. The addition of Sc element can not only cause the constitutional undercooling at the interface of solidification interface, but also reduce the misfit degree and interfacial energy between the primary Al₃Fe phase and the matrix. Thus, the primary Al₃Fe phase was greatly refined.Electric current treatment of 59A/dm² was acted on the hypereutectic Al-5％Fe alloy containing 0.4％Sc. It was found that the size of primary Al₃Fe phase was reduced obviously, the particle-like primary Al₃Fe phase looked much more finer, the short needle-like primary Al₃Fe phase was reduced, and the morphology of the alloy was apparently improved. Electric current treatment of 59A/dm² was exerted on the hypereutectic Al-5%Fe alloy with addition of 1%Al-5Ti-0.25C. It was observed that the size of primary Al₃Fe phase was further reduced, and appeared to be fine needle-like and particle-like.更多还原