beta-grain size effect on the 18R-martensite microestructure in Cu-based SMA

P. LA ROCA, L. ISOLA, PH. VERMAUT, J. MALARRIA

Procedia Materials Science

ELSEVIER SCIENCE SA

Año: 2015 vol. 8 p. 1133 - 1139

2211-8128

A systematic experimental analysis based on the assessment of the mean martensite plate size in sub-grain domains was implemented to characterize the martensitic microstructure morphology in polycrystalline Cu-based shape memory alloys. Experimental data was collected by light and electron microscopy, analyzing polycrystalline materials of grain size (d) in a wide range: from finegrained material with grain size of about 500 nm (ribbons and strips obtained by rapid solidification techniques ) to single-crystals of 6mm diameter (grown by the Bridgman method). In the d range below 100 μm, a lineal relationship between the average width of the martensite plates (hplate) and the mean grain size was obtained for thermal-induced martensite transformation (TMT). Above this value (d > 100 μm), such relation is no longer valid, and hplate becomes independent of grain size.