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采用区域熔炼液态金属冷却定向凝固法制备具有择优取向的Ni_(52)Fe_(17)Ga_(27)Co_4磁性形状记忆合金,借助OM,SEM和EBSD研究了稳定生长区的组织特征和择优取向.结果表明,在低温度梯度和高凝固速率下,晶体沿〈100〉方向生长,但生长不稳定,存在初生γ相;当提高温度梯度和降低凝固速率后,晶体沿〈110〉方向生长,柱状晶大小均匀,无γ相,室温时为沿(222)面取向的马氏体单相组织.马氏体孪晶孪生面为(110)和(110),内部无微孪晶;在马氏体组织中,观察到了条状分布的磁畴.理论分析结果表明,晶体稳定生长的条件为高的温度梯度和低的凝固速率.在该条件下获得了大体积稳定马氏体单变体区.
The Ni_ (52) Fe_ (17) Ga_ (27) Co_4 magnetic shape memory alloy with preferred orientation was prepared by the zone smelting liquid metal cooling directional solidification method. The microstructure and the preferred orientation of the stable growth zone were studied by means of OM, SEM and EBSD. The results show that the crystal grows in the <100> direction at low temperature gradient and high solidification rate, but the growth is unstable and the primary γ phase exists. When the temperature gradient is increased and the solidification rate is decreased, the crystal grows in the <110> direction. The crystal size is uniform and without γ phase, and martensite single phase structure oriented along (222) plane at room temperature.The twin planes of martensite twin are (110) and (110) The distribution of the magnetic domains was observed in the body tissue.The theoretical analysis shows that the stable growth conditions of the crystal are high temperature gradient and low solidification rate.A large volume stable martensite single variant region .