Shape memory effect of dual-phase NiMnGaTb ferromagnetic shape memory alloys
Shape memory effect of dual-phase NiMnGaTb ferromagnetic shape memory alloys
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DOI：
10.1007/s42243-018-0144-x
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发表时间：
2018-11
影响因子：
2.5
通讯作者：
Jiang Zhang;Yong-hong Ma;Ruo-lin Wu;Jingmin Wang
中科院分区：
文献类型：
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作者：
Jiang Zhang;Yong-hong Ma;Ruo-lin Wu;Jingmin Wang
研究了铸态和定向凝固NiMnGaTb双相合金的组织演变、逆马氏体相变及其对形状记忆效应的影响。当抽拉速率分别为10、50、200和1000 μm/s时，定向凝固合金组织为单晶组织、择优枝晶组织和杂乱枝晶组织。定向凝固合金的析出相弥散分布在马氏体基体中。随着晶粒和颗粒析出物的细化，逆马氏体相变逐渐向较低温度移动，温度跨度显著加宽。定向凝固技术可以有效地提高形状记忆效应恢复应变（εsme），通过实现择优取向，降低触发孪晶再取向所需的压应力（σ），最大ε sme可达4.96%，最小σ可达14 MPa inv= 10 μm/s。枝晶形貌的形成降低了形状记忆应变，ε sm随二次枝晶臂的长大而减小。
The evolution of microstructure, reverse martensitic transformation and the correlated influence on shape memory effect was investigated in as-cast and directionally solidified dual-phase NiMnGaTb alloys. The directionally solidified alloys exhibit single-crystal microstructure, preferred dendrite microstructure, and mussy dendrite microstructure in the specimens grown at a withdrawal rate (v) of 10, 50 and 200, and 1000 μm/s, respectively. The precipitates dispersively distribute in the martensite matrix for the directionally solidified alloys. With the refined grains and particle precipitates, the reverse martensitic transformation gradually shifts to lower temperatures and the temperature span is significantly broadened. The directional solidification technology can effectively enhance the strains recovered due to shape memory effect (εsme) and decrease the compressive stress required to trigger the reorientation of twins (σ) via the realization of preferred orientation, while the maximalεsmeand minimumσcan reach 4.96% and 14 MPa inv= 10 μm/s specimens, respectively. The formation of dendrite morphology degrades the shape memory strain, andεsmedecreases with the growth of secondary dendritic arms.