Deciphering M-T diagram of shape memory Heusler alloys: reentrance, plateau and beyond

We present our recent results on temperature behaviour of magnetization observed in Ni_47Mn_39In_14 Heusler alloys. Three regions can be distinguished in the M-T diagram: (I) low temperature martensitic phase (with the Curie temperature T_CM = 140 K), (II) intermediate mixed phase (with the critical temperature T_MS = 230 K) exhibiting a reentrant like behavior (between T_CM and T_MS) and (III) high temperature austenitic phase (with the Curie temperature T_CA = 320 K) exhibiting a rather wide plateau region (between T_MS and T_CA). By arguing that powerful structural transformations, causing drastic modifications of the domain structure in alloys, would also trigger strong fluctuations of the order parameters throughout the entire M-T diagram, we were able to successfully fit all the data by incorporating Gaussian fluctuations (both above and below the above three critical temperatures) into the Ginzburg-Landau scenario

Real-time study of high-cycle fatigue damage using the averaged speckle dynamics

The theory of the method permitting a study of damage accumulation in high-cycle fatigue of reflecting and transparent objects using the time-averaged speckle images is briefly discussed. The formulas that relate the relative displacement vector of the scattering centres to the time-average intensity and the temporal autocorrelation function of this intensity at some observation point are presented. A technique identifying the component of the relative displacement vector as local plastic deformations emerge during fatigue testing is discussed. The issue of real-time recording and processing of the speckle images using the conventional personal computers and special-purpose video systems with function-oriented processors based on homogenous computing environment is discussed. Processors with homogenous architecture allow assurance of the highest possible image processing performance within the order of 10-teraflops/s. The specimens, the optical system, the equipment for fatigue testing, the USB camera and the software used in high-cycle fatigue experiments are discussed. The possibilities and prospects for application of this technique and equipment in evaluation of the remaining life of some object types are discussed. © 2019 Published under licence by IOP Publishing Ltd

Research of magnetocaloric effect of Ni-Mn-In-Co- based Heusler alloys by the direct method in magnetic fields up to 14 T

IEEE International Magnetics Conference, INTERMAG 2017 ( 2017. Dublin; Ireland