Effect of high intensity ultrasonic treatment on microstructural modification and hardness of a nickel-aluminum bronze alloy

The effect of high intensity ultrasonic treatment (HIUST) at different pouring temperatures for the application time of 100 s on microstructural modification and hardness of a nickel-aluminum bronze (NAB) alloy has been studied. The chemical composition of the investigated alloy is Cu-10Al-5Fe-5Ni. The results show clearly that in the absence of HIUST, the coarser dendritic α(Cu) phases and coarser β′ phases are formed with a nonuniform distribution of coarser intermetallic κII phase particles which are based on Fe3Al in the interdendritic regions. Upon HIUST of this alloy during solidification process, finer equiaxed α(Cu) phases and finer β′ phases with a uniform distribution of finer intermetallic κII phase particles along the cast structure can be obtained at optimum pouring temperature of 1090 °C. The highest hardness of ultrasonic treated alloy can be achieved at the optimum pouring temperature of 1090 °C. The refinement and modification mechanisms resulting in development of microstructure are also investigated.