Thermo-mechanical effects caused by martensite formation in powder metallurgy FeMnSiCrNi shape memory alloys


Pricop B., Mihalache E., Stoian G., Borza F., Özkal B. , Bujoreanu L.

POWDER METALLURGY, vol.61, no.4, pp.348-356, 2018 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 61 Issue: 4
  • Publication Date: 2018
  • Doi Number: 10.1080/00325899.2018.1492773
  • Title of Journal : POWDER METALLURGY
  • Page Numbers: pp.348-356

Abstract

The paper reports solution treatment (ST) and mechanical alloying (MA) effects on the structure and static/dynamic mechanical behaviour of PM-MA'ed FeMnSiCrNi shape memory alloys associated with the formation of thermally and stress-induced martensite. The specimens were subjected to tensile pre-straining, in order to stress induce martensite and their gauges were cut and prepared for X-ray diffraction (XRD) as well as for optical and scanning electron microscopy (SEM). XRD patterns allowed determining the presence of large amounts of alpha'-body centred cubic (bcc) besides epsilon-hexagonal close packed (hcp) martensite and gamma-face centred cubic (fcc) austenite. The decrease in the amount of alpha'-bcc at specimens ST'ed at 1273 and 1373 K, with increasing pre-straining degree, was confirmed by XRD patterns and SEM micrographs. Dynamic mechanical analysis (DMA) was performed by strain sweeps (SS). The SS-DMA graphs displayed storage modulus plateaux which were associated with the formation of epsilon-hcp martensite.