Abstract: The transmission electron microscopy has been used to investigate the fine structure variation of 18R martensite under deformation in a polycrvstalline CuZnAl shape memory alloys.It has been found that the strain is gabined by the reorientation of martensite variants in the ini- tial deformation stage.In addition to the result of optical microscopy studies,however,the reorientation is often incomplete and the interfaces among the prior variants still remain.A lot of twins will appear in martensite under enormous deformation,and the twin plane is(001) phane of martensite lattice.The dislocations has also been observed in some regions.In this case,the martensite will lose its thermoelasticitv and the shape memory effect will be damaged.

Key words: fine structure, shape memory alloy, CuZnAl alloy, martensitic transformations