Magnetic indication of the stress-induced martensitic transformation in ferromagnetic Ni-Mn-Ga alloy

A quantitative study of the stress-induced martensitic transformation in Ni49.7Mn29.1Ga21.2 Magnetic shape memory alloy has been carried out in two different ways: the first way is based on the measurements of saturation magnetization under variable mechanical stress and the second one is founded on the quantitative theoretical treatment of experimental stress-strain loops. A functional dependence between the Volume fraction of transformed martensite and applied stress has been determined from both magnetization and strain values. A quantitative agreement between the functions determined in two different ways has been observed, and hence, the effectiveness of the magnetic indication of the stress-induced martensitic transformations has been proved. This method can be used to monitor stress-induced transformations in martensitic films, needles and small specimens. (c) 2005 Elsevier B.V. All rights reserved.