Gaining flexibility on the design of microstructure, texture and shape memory properties in an Fe-Mn-Si-Cr-Ni alloy by ECAE and annealing

A.V. DRUKER; A. BARUJ; L. ÍSOLA; V. FUSTER; J. MALARRÍA; R. BOLMARO

MATERIALS & DESIGN

ELSEVIER SCI LTD

Lugar: Amsterdam; Año: 2016 vol. 107 p. 153 - 162

0261-3069

The effect of ECAE on the properties of an Fe-15Mn-5Si-9Cr-5Ni shape memory alloy (SMA) was investigated. Phases, texture, microstructure, critical temperatures, mechanical and SM properties after severe deformation, and the effect of annealing were analysed. One ECAE pass develops a shear texture. There is a large <101> component in the extrusion direction, which is near the ideal <414> for martensitic transformation activation. The pressing did not refine the previous as cast structure but introduced dislocations and épsilon-martensite. Thus, the stress to induce the gamma to épsilon martensitic transformation, sigmagamma-épsilon, reached 620 MPa, and the quantity of épsilon-martensite formed after compression was limited. The degree of shape recovery was reduced, while the reverse transformation temperatures increased. Heat treatments above 800 ºC activated recrystallization. As annealing temperature increased, new grains nucleated and grew, reaching a size of 53 mm after heating to 1000 ºC. For this condition, sigmagamma-épsilon was 430 MPa, and the best shape recovery was achieved, 64 %.