Effect of rapid solidification and post-processing on microstructure, magnetic and structural transition temperatures and magnetic properties in Ni50Mn29Ga21 magnetic shape-memory alloy
Effect of rapid solidification and post-processing on microstructure, magnetic and structural transition temperatures and magnetic properties in Ni50Mn29Ga21 magnetic shape-memory alloy
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快速凝固和后处理对Ni50Mn29Ga21磁性形状记忆合金显微组织、磁性和结构转变温度以及磁性能的影响
DOI：
10.1016/j.actamat.2023.119325
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发表时间：
2023
期刊：
影响因子：
9.4
通讯作者：
Fink, Carolin
中科院分区：
文献类型：
--
作者：
Flitcraft, Emily;De Vecchis, Pierangeli Rodriguez;Kuprienko, Alexey;Chmielus, Markus;Fink, Carolin
研究了快速凝固和后处理工艺对Ni 50 Mn 29 Ga 21（at.%）合金组织、成分和磁结构性能的影响。磁性形状记忆合金（MSMA）。采用电弧熔炼法制备了不同冷却速率（1.1 × 102 ~ 3.2 × 103 K/s）的试样，并对凝固态和两种不同热处理后的试样进行了对比研究。在更快速的凝固过程中，观察到了从柱状枝晶到胞状枝晶的显著变化以及凝固长度尺度的减小。所有样品均表现出亚晶界处Mn富集和相应的Ga贫化。细尺度凝固组织、化学不均匀性和无序性导致了宽范围的马氏体相变。在更快速的凝固，饱和磁化强度的下降和异常的斜率变化的磁滞回线进行了观察。热处理导致晶粒长大，显着减少的转变宽度，并增加磁化饱和。快速凝固样品的特征冷却速率估计为1.1 × 103 K/s，最接近的微观结构和磁结构性能的激光定向能量沉积（L-DED）处理。这项研究的结果有助于了解L-DED增材制造的Ni-Mn-Ga中的冷却速率效应，并提供后处理路线，这些路线将导致类似于功能性MSMA的微观结构和性能。
This study investigated the effect of rapid solidification and post-processing on microstructure, composition and magneto-structural properties of Ni50Mn29Ga21(at.%) magnetic shape memory alloy (MSMA). Samples with varying cooling rates (1.1 ∙ 102to 3.2 ∙ 103K/s) were prepared using arc melting for a comparative study in as-solidified condition and after two different heat treatments. A notable change from columnar-dendritic to cellular-dendritic solidification and a decrease in solidification length scale was observed at more rapid solidification. All samples showed Mn enrichment and corresponding Ga depletion at the sub-grain boundaries. The fine-scale solidification structure, chemical heterogeneity and lack of ordering resulted in broad martensitic transformations. At more rapid solidification, a decrease in saturation magnetization and abnormal slope changes in the hysteresis loop were observed. Heat-treatment resulted in grain growth, significant reduction in transformation breadth, and increase in magnetization saturation. Rapidly solidified samples with an estimated characteristic cooling rate of 1.1 ∙ 103K/s most closely resembled microstructures and magneto-structural properties from laser directed energy deposition (L-DED) processing. The results of this study help to understand cooling rate effects in L-DED additive manufactured Ni-Mn-Ga and provide post-processing routes that will result in microstructures and properties that resemble those of functional MSMA.