Martensitic Transformation in a Cu-Zn-Sn Alloy.

A study is made of the low-temperature ( beta prime reversible reaction beta double prime ) martensitic transformation in the alloy Cu plus 34. 7 wt% Zn plus 3 wt% Sn. It is found that the direct beta prime yields beta double prime martensitic transformation occurs in the temperature range from plus 5 to minus 65 degree C, while the inverse transformation begins at minus 50 degree C and terminates at plus 20 degree C. Only by sudden quenching in an aqueous solution of NaOH cooled to 0 degree C can the initial parent beta prime -phase be immobilized and the diffusion processes of alpha -phase precipitation be prevented. The alpha -phase is precipitated according to bainite kinetics from the beta prime -phase at 190-325 degree C. Recovery of the shape of deformed samples of beta double prime -phase occurs mainly as a result of recovery of the shape and orientation of the beta prime -phase during the inverse martensitic transformation.