Orientation relationships of martensite variants determined by electron backscatter diffraction

Orientation relationships between the parent phase and 2H type martensite, and between different variants in a plate group of martensite in the CuAlNi shape memory alloy were determined by electron backscatter diffraction. Th e result reveals clearly that the basal planes of different correspondence variants of the 2H martensite originate from different {110}(p) planes of t he parent phase, and the [010](2H) axis of each correspondence variant orig inates from one of the [001](p) axes of the parent phase. Our result reveal s also the typical relationships of four habit-variants A, B, C and D in a martensite plate group, and that the habit-variants A and C land equivalent ly B and D) are twin-related by an {121}(2H) mirror plane, and the habit-va riants A and D land B and C) are twin-related by an {101}(2H) mirror plane. Usually, variants A and C land B and D) form spear morphology and variants A and D land B and C) form fork morphology. (C) 1999 Elsevier Science Ltd. All rights reserved.