Grain refinement and Al-water reactivity of Al-Ga-In-Sn alloys

Al-Ga-In-Sn alloys were prepared by using traditional casting metallurgy method with different additions of Al-5Ti-1B grain refiner. Their microstructures were investigated by means of X-ray diffraction (XRD) and scanning electron microscope (SEM) with energy dispersed X-ray (EDX). The Al grains of alloys are refined significantly from 129 mu m to 57 mu m with increasing Ti content from 0.03 wt% to 0.24 wt%. Many thin dendrites that are a few micrometers thick are observed within Al grains. Al-water reactivities were performed under different water temperatures. The alloy with Ti content of 0.12 wt% shows the maximum H-2 generation rate under different water temperatures, which is above 5 times of Ti-free alloy. The H-2 yields of alloys drop from 87% to 30% with rising Ti content from 0.03 wt% to 0.24 wt% at the water temperature of 30 degrees C, but they rise to about 90% when the water temperature is above 50 degrees C. The growth mechanism of alloys and the effect of grain refinement on Al-water re activities are discussed. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.