摘要
Transmission electron microscopy was performed to investigate the microstructure and precipitates in the annealed Co38Ni33Al29 ferromagnetic shape memory alloy. Apart from the dendritic secondary phase in the austenite matrix, micron-sized (up to 100 mu m) fcc-based precipitates with partial gamma%26apos; L1(2) ordering and containing none, one or three {1 1 1}(p) parallel twin planes were found. The orientation relationship between the precipitates and matrix was found to be Kurdjumov-Sachs. STEM-EDX analysis indicates that twinned and non-twinned precipitates are Co-rich and Al- and Ni-deficient with respect to the matrix and with a lower Co/Al ratio for the latter. The 3D morphologies of precipitates were reconstructed with focused ion beam/scanning electron microscope dual-beam slice-and-view imaging, showing that the single {1 1 1}(p) plane twinned precipitates have a plate-like shape while the non-twinned precipitates are lath-like and often bent.
- 出版日期2013-9-25