Combination and Interface Structure of 9R Martensite Plate Variants in Ti_50.0Pd_43.0Fe_7.0 Shape Memory Alloy

Abstract

The combination of 9R martensite plate variants in Ti_50.0Pd_43.0Fe_7.0 shape memory alloy has been investigated by conventional transmission electron microscopy (CTEM). Three fundamental combinations of plate variants are identified in the plate group. These are designated as A:B, A:C and A:D types, which correspond to ⟨\\bar591⟩_9R Type II, {11\\bar4}_9R Type I and {105}_9R compound twins, respectively. They show the same morphological characteristics of 9R and 18R martensite in Cu-base shape memory alloys, i.e., wedge, spear and fork (or kink) types. The Type II and compound twins are new findings. Irrational nature of the A:B interface is also studied in the edge-on state by high resolution electron microscopy (HREM). The boundary is gradually and randomly curved with strain contrast.