Transmission electron microscopy investigation of microstructures in low-hysteresis alloys with special lattice parameters

A sharp drop in hysteresis is observed for shape memory alloys satisfying the compatibility condition between austenite and martensite, i.e. lambda(2) = 1, where lambda(2) is the middle eigenvalue of the transformation strain matrix. The present work investigates the evolution of microstructure by transmission electron microscopy as the composition of the Ti(50)Ni(50-x)Pd(x) system is systemically tuned to achieve the condition lambda(2) = 1. Changes in morphology, twinning density and twinning modes are reported along with twinless martensite and exact austenite-martensite interfaces. (C) 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.