Acoustic emission of Ni–Mn–Ga magnetic shape memory alloy in different straining modes
Acoustic emission of Ni–Mn–Ga magnetic shape memory alloy in different straining modes
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DOI：
10.1016/j.msea.2004.03.018
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发表时间：
2004-06
期刊：
影响因子：
6.4
通讯作者：
L. Straka;V. Novák;M. Landa;O. Heczko
中科院分区：
文献类型：
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作者：
L. Straka;V. Novák;M. Landa;O. Heczko
利用声发射（AE）实验研究了Ni49.7Mn29.1Ga21.2单晶样品的磁致应变（磁形状记忆效应）。在热和应力诱导的马氏体相变和压缩应力诱导的马氏体再取向过程中的AE进行监测。测量了应力诱导转变的部分循环。所有过程都是声学活动。最高的AE活动检测在应力诱导的转变从马氏体到奥氏体后卸载。在应力诱导的正向和反向转化过程中观察到的AE活动之间的差异可能归因于不同的动力学转化过程。奥氏体在加载和卸载期间以及在热循环期间保持声学不活跃。马氏体在应力诱导的再取向期间、在加载和卸载期间表现出声学活动，并且在热循环期间表现出较低的活动。这种声学活动可以暂时归因于孪生过程。
We investigated a Ni49.7Mn29.1Ga21.2single crystalline sample exhibiting 5.7% magnetic-field-induced strain (magnetic shape memory effect) by means of acoustic emission (AE) experiments. The AE was monitored during thermally- and stress-induced martensitic transformations and during compressive stress-induced martensite reorientation. Partial cycles were measured for the stress-induced transformation. All processes are acoustically active. The highest AE activity was detected during stress-induced transformation from martensite to austenite upon unloading. Observed difference between AE activity during stress-induced forward and reverse transformations might be attributed to different dynamics of transformation processes. Austenite remains acoustically inactive during loading and unloading as well as during thermal cycling. Martensite exhibits acoustic activity during stress-induced reorientation, during loading and unloading, and lower activity during thermal cycling. This acoustic activity can be tentatively ascribed to twinning processes.