By means of DSC, three transformations occurring on heating up to 873 K, of a martensitic Cu63Al26Mn11 Shape Memory Alloy (SMA) in hot pressed and homogenized state, were revealed. The assumed precipitation of α-phase, accompanied by an exothermic reaction, was ascertained by SEM mapping. SEM micrographs revealed preferred orientation tendencies for the α-phase precipitates, inside the grains which became more prominent along grain boundaries

Bainite transitory formation, during the heating of a martensitic copper base SMA, was predicted by DSC and DTA and confirmed by XRD, OM and TEM only in hot pressed air cooled state homogenized and tempered at 573 K. In this heat treatment state, due to the pre-existence of α-phase, bainite amount is expected to be too low, therefore nondistinguishable, for higher tempering temperatures, where it is suggested that transitory α1 bainite turned to

Different fragments of martensitic Cu-14.86 Zn-5.81 Al-0.5 Fe (mass. %) shape memory alloy were subjected to heating, up to 453 K, with different rates ranging from 1 K×1.66×10 2 s 1 to 54.6×1.66×10 2 s 1, performed by means of a differential scanning calorimeter. In all cases, during heating, an endothermic peak was observed which was associated with the martensite reversion to parent phase. By means of the differential scanning calorimeter

Temperature memory effect (TME) is usually manifested by a kinetic stop during reverse transformation of thermally induced martensite to parent phase, after performing an incomplete heating in the previous thermal cycle, applied to a shape memory alloy (SMA). Technically TME causes the splitting of the endothermic peak corresponding to martensite reversion, on differential scanning calorimetry (DSC) thermograms. The present paper illustrates new

By means of simultaneous thermal analysis (STA), comprising differential scanning calorimetry (DSC) and thermal gravimetry (TG), a repetitive solid state transformation has been observed which was associated with Ni ferromagnetic-paramagnetic transition within the powders of an Fe-based shape memory alloy (SMA) with nominal composition Fe-14 Mn-6 Si-9 Cr-5 Ni (mass. %). During thermal cycling up to 773 K an obvious exothermic step on heating and

In this study sintering behaviour of Fe-Mn-Si based powder metal system were investigated using vertical dilatometer. Grain size refinement of key target composition alloys performed via mechanical alloying by taking advantage of high energy milling equipment. Both powder state and sintered state phases were characterized via XRD studies and effect of mechanical alloying time against sintering densification of Fe-Mn-Si based powder metal system were

A fragment of a Cu-15Zn-6Al (mass%) shape memory alloy (SMA), in hot rolled-water quenched condition,was subjected to thermal cycling performed by means of a differential scanning calorimetry (DSC) device.Each cycle comprised controlled heating, isothermal maintaining, and free air-cooling, repeated three times,up to maximum temperatures increased by every 10 K, between 450 and 490 K, aiming to reproduce actual functioning conditions of a SM electrical

Specimens from Fe-Mn-Si-Cr-Ni SMA, obtained by powder metallurgy and compacted through hot rolling, were subjected to tensile loading-unloading cycles. The pseudoelastic parameters were determined based on recorded stress-strain curves, and their variation tendency with increasing the number of mechanical cycles was discussed. The gauges of tensile specimens were cut after mechanical cycling and were subjected to structural and dilatometric analysis.

By means of tensile stress variation during heating-cooling, applied in each consecutive cycle, performed up to progressively higher strains, the constrained recovery behaviour of a Fe-15.8 Mn-3.8 Si-12.3 Cr-4.7 Ni (mass. %) shape memory alloy (SMA) was reported. During each cycle, temperature was increased from room temperature up to 453 K and decreased to room temperature, while keeping the specimen to a constant strain. The variation tendencies

The influence of microstructure on the stress–strain behavior of an Ni-rich NiTi shape memory alloy is examined. Specimens cut from a large diameter-bar of Ni50.7Ti49.3 shape memory alloy were analyzed in two states: (i) annealed and (ii) annealed and aged. The annealed state shows a fully austenitic structure with no precipitates and no distortions caused by residual stresses. The annealed and aged state has coherent Ni4Ti3 particles precipitated