Influence of Grain Size and Ordering on the Two Way Shape Memory Effect in CuAlMn Alloys

¹ Institute of Metallurgy and Materials Science of the Polish Academy of Sciences, 30-059 Kraków ul.Reymonta 25, Poland
² Physics Department, University of Balearic Islands, 07071 Palma de Mallorca, Cra de Valldemossa km. 7.5, Spain

Abstract

Two way shape memory effect (TWSME) in CuAIMn alloys was studied in samples of various grain sizes and a degrees of order. The training was performed by cooling the samples under tensile stress below M_f and heating above A_f after unloading. It was found that investigated alloys showed well developed TWSME already 10 cycle s.Increasing of the training stress caused broadening of the transformation hysteresis. Training treatment causes formation of dislocation stacks of increased density at higher training stress. Most of dislocations possess a mixed character of Burgers vector (u = <111>, b = <100>), however some dislocations of b = <100> were observed in g•b contrast experiments. At higher training stress relatively large amount of stabilised 2H or 18R martensite was found which is most probably related to the training effect.