Influence of mechanical alloying on the behavior of Fe-Mn-Si-Cr-Ni shape memory alloys made by powder metallurgy


Pricop B., SOYLER U., Özkal B. , LOHAN N. M. , PARASCHIV A. L. , SURU M. G. , ...More

9th European Symposium on Martensitic Transformations (ESOMAT 2012), St Petersburg, Russia, 9 - 16 September 2012, pp.237-238 identifier identifier

Abstract

Fe-14 Mn-6 Si-9 Cr-5 Ni (mass. %) shape memory alloys (SMAs) were produced from raw powders employed both in initial commercial state and in a mixture state of equal fractions of commercial and mechanically alloyed (MA'd) particles. After blending, pressing and sintering, powder compacts were hot rolled (HR'd) and solution treated (ST'd) before being machined into plane-parallel lamellas. Specimens with special geometry were pre-strained on a tensile testing machine. By means of X-ray diffraction (XRD) and scanning electron microscopy (SEM) the presence of epsilon hexagonal close packed and alpha' body center cubic stress induced martensites was revealed and their thermally induced reversion to gamma face center cubic austenite was evaluated by modulated differential scanning calorimetry (MDSC). The results enabled the study of the influence of MA, HR, ST and pre-straining on phase structure and associated on shape memory effect (SME). The lamellas were hot formed into rings, which were trained in bending. Diameter reduction of trained enlarged rings, on heating, was monitored by cinematographic analysis.