Deformation Characteristics and Texture Development of Biadded Cu-29Zn Alloys

Abstract

Theories regarding texture transition mechanisms of brass alloys and its critical deformation level of when the change of texture transition occurs are still in debate. Previous observation showed that copper type texture dominantly formed at high temperature process whereas brass type texture tended to occur at low temperature. In contrast, another research observed the occurrence of copper type texture at low strain level while higher strain level resulted in brass type texture. Thus further research is needed to affirm one that well-satisfy the actual texture transition phenomenon. In this research, Cu-Zn-xBi alloys were produced by gravity casting process using pure Cu and Zn ingots with varied Bi addition of 0.2, 0.4, and 0.8 wt. %. As-cast samples were homogenized at 800 °C for 2 h in a muffle furnace. The samples were then cold-rolled with the level of deformation of 20, 40, and 70 %. Characterization includes chemical composition analysis, microstructure observation, hardness testing, and texture measurement. Results showed that addition of Bi prompted Bi-rich dispersoid phase which segregated inside the grain and along the grain boundary in globular forms. Slip was dominant at 20 % deformation level and its density increased with the addition of Bi. At 40 % deformation, twinning replaced slip as the predominant mechanism. The twin density increased with higher Bi content. Further deformation at 70% produced shear bands and flattened the Bi dispersoid phase. Greater Bi content induced the formation of shear band. At 40% deformation, pole figure images show the trend of copper type texture with orientation of {112} <111> with intensity of 7.92. This texture was formed by mechanical twinning during deformation process. At 70 % deformation, samples illustrated the combination of brass and Goss type texture at orientation of {110} <112> and {110} <001> due to the shear band.