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The Sn-10.2 Sb (mass fraction) peritectic alloy was prepared using a vacuum melting furnace and a hot filling furnace. The samples were directionally solidified upwards at steady state conditions with a constant temperature gradient (G=4.5±0.2 K. mm -1 ) under different growth velocities (V=13.3-266.7 µm. s -1 ) in a Bridgman-type directional solidification apparatus. The effects of the growth velocity (V) on the dendritic spacings were investigated. Primary dendrite arm spacing (PDAS) of α phase in directionally solidified Sn-10.2 Sb peritectic alloy was measured on the longitudinal and transverse sections of 4 mm diameter cylindrical samples. Secondary dendrite arm spacing (SDAS) was measured on the longitudinal section. The experimental results show that the measured PDAS (λ 1L , λ 1T ) and SDAS (λ 2 ) decrease with increasing growth velocity. The dependence of PDAS, SDAS, microhardness (HV) and compressive strength (σ c ) on the growth velocity were determined by using a linear regression analysis. The experimental results were compared with the previous experimental results and the results of the experimental models.

The Al-5.5Zn-2.5Mg (wt pct) ternary alloy was prepared using a vacuum melting furnace and a casting furnace. Five samples were directionally solidified upwards at a constant temperature gradient (G = 5.5 K/mm) under different growth rates (V = 8.3-165 lm/s) in a Bridgman-type directional solidification furnace. The primary dendrite arm spacing, k 1 , secondary dendrite arm spacing, k 2 , and microhardness, HV, of the samples were measured. The effects of V on k 1 , k 2 and HV properties of the Al-Zn-Mg alloy were studied by microstructure analysis and mechanical characterization. Microstructure characterization of the alloys was carried out using optical microscopy, scanning electron microscopy, wavelength-dispersive X-ray fluorescence spectrometry, and energy dispersive X-ray spectroscopy. From the experimental results, it is found that the k 1 , k 2 values decrease, but HV values increase with the increase in V, and HV values decrease with the increase in k 1 and k 2 . Dependencies of dendritic spacing and microhardness on the growth rate were determined using linear regression analysis. The growth rate, microstructure, and Hall-Petch-type relationships obtained in this work have been compared with the results of previous studies.

Aluminium and its alloys are used in all bare overhead energy transmission lines. Researchers and manufacturers, have in the past, made significant improvements in the tensile strength and conductivity of overhead lines. In the present work, the effect of heat treatments on the tensile strength of Al-Zr alloys (Al-0.15, 0.20, 0.25wt.%Zr) has been investigated (all compositions hereafter are described in wt.%). The Al-Zr samples were prepared by using a melt furnace and a continuous casting line. The cast, extruded and drawn samples with different diameters (4, 6, 10 mm) were aged isothermally and isochronally in muffle and tube furnaces. Aging was performed over a wide range of temperatures (350-450 °C) at constant aging times (100 hrs., 125 hrs.) and over a wide range of aging times (50-150 hrs.) at a constant temperature (425 °C). It was found that, aging temperatures, aging times, composition, processing techniques and size of the samples affect the tensile strength.