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Zn-5wt% Al eutectic alloy was directionally solidified with different growth rates (5.32-250.0μm/s) at a constant temperature gradient of 8.50 K/mm using a Bridgman-type growth apparatus.The values of eutectic spacing were measured from transverse sections of the samples.The dependences of the eutectic spacing and undercooling on growth rate are determined as λ=9.21V-0.53 and ΔT=0.0245V0.53,respectively.The results obtained in this work were compared with the Jackson-Hunt eutectic theory and the similar experimental results in the literature.Microhardness of directionally solidified samples was also measured by using a microhardness test device.The dependency of the microhardness on growth rate is found as Hv=115.64V0.13.Afterwards,the electrical resistivity (r) of the casting alloy changes from 40×10-9 to 108×10-9 Ω·m with the temperature rising in the range of 300-630 K.The enthalpy of fusion (ΔH) and specific heat (Cp) for the Zn-Al eutectic alloy are calculated to be 113.37 J/g and 0.309 J/(g·K),respectively by means of differential scanning calorimetry (DSC) from heating trace during the transformation from liquid to solid.
Zn-5wt% Al eutectic alloy was directionally solidified with different growth rates (5.32-250.0μm / s) at a constant temperature gradient of 8.50 K / mm using a Bridgman-type growth apparatus. Values of eutectic spacing were measured from transverse sections of the samples of dependence of the eutectic spacing and undercooling on growth rate are determined as λ = 9.21V-0.53 and ΔT = 0.0245V0.53, respectively. The results obtained in this work were compared with the Jackson-Hunt eutectic theory and the similar experimental results in the literature. Microhardness of directionally solidified samples was also measured by using a microhardness test device. The dependency of the microhardness on growth rate is found as Hv = 115.64V0.13.Afterwards, the electrical resistivity (r) of the casting alloy changes from 40 × 10-9 to 108 × 10-9 Ω · m with the temperature rising in the range of 300-630 K. The enthalpy of fusion (ΔH) and the specific heat (Cp) for the Zn-Al eutectic alloy are calculated to be 113.37 J / g and 0.309 J / (g · K), respectively by means of differential scanning calorimetry (DSC) from heating trace during the transformation from liquid to solid.