Unidirectional solidification of Zn-rich Zn-Cu hypoperitectic alloy

Zn-0.7 wt% Cu-hypoperitectic alloy was prepared in a graphite crucible under a vacuum atmosphere. Unidirectional solidification of the Zn-0.7 wt% Cu-hypoperitectic alloy was carried out by using a Bridgman-type directional solidification apparatus under two different conditions: (i) with different temperature gradients (G = 3.85-9.95 K/mm) at a constant growth rate (41.63 mu m/s) and (ii) with different growth rate ranges (G = 8.33-435.67 mu m/s) at a constant temperature gradient (3.85 K/mm). The microstructures of the directionally solidified Zn-0.7 wt% Cu-hypoperitectic samples were observed to be a cellular structure. From both transverse and longitudinal sections of the samples, cellular spacing (lambda) and cell-tip radius (R) were measured. The effects of solidification-processing parameters (G and V) on the microstructure parameters (lambda and R) were obtained by using a linear regression analysis. The present experimental results were also compared with the current theoretical and numerical models and similar previous experimental results.