退火温度对(La,Y)-Mg-Ni-Al合金气态吸放氢性能影响

Effect of Annealing Temperature on Gaseous Hydrogen Absorption and Desorption Performance of(La,Y)-Mg-Ni-Al Alloy

为了探究La0.62Y0.2Mg0.18Ni3.30Al0.20合金具有良好气态吸放氢性能的适宜退火温度,采用XRD、OM分析了铸态及退火合金的相结构及金相组织,用SEM观察了吸放氢前后合金颗粒的表面形貌,用压力-组成-温度(PCT)仪测试了合金的PCT特性以及吸放氢动力学性能。结果表明,900℃退火合金含有LaNi5和(La,Y,Mg)2(Ni,Al)7主相以及Ni3Y残余相。随着退火温度升高,主相不变,但Ni3Y转变成Y2Ni7相;主相晶胞体积先增大后减小,在41~43°衍射角度内,半高宽先减小后增大。与铸态及其他温度退火合金相比,950℃退火合金的组织均匀性较好,吸放氢量、平均吸放氢速率较高,吸放氢的氢压和滞后系数较小。综合比较,实验范围内,合金的适宜退火温度为950℃。

In order to find the suitable annealing temperature of La0.62Y0.2Mg0.18Ni3.30Al0.20 alloy with excellence gaseous hydrogen absorption and desorption performance,phase composition and metallographic microstructure of the as-cast and annealed alloy were analyzed by XRD and OM,surface morphology of alloy particles before and after hydrogen absorption and desorption was observed by SEM,and PCT characteristics and dynamic performance of hydrogen absorption and desorption of the alloy were tested by pressurecomponent-temperature（PCT）apparatus.The results show that annealed alloy at 900℃contains the main phases of LaNi5and（La,Y,Mg）2（Ni,Al）7and Ni3 Y residual phase.With annealing temperature increasing,the main phases are unchanged but Ni3 Y phase is transformed into Y2Ni7 phase,and its cell volume increases at first and then decreases and FWHM firstly decreases and then increases within 41-43°diffraction angle.Compared with the as-cast alloy and the annealed alloy at 900℃,1 000℃and 1 050℃,the annealed alloy at 950 ℃ has better microstructure uniformity,and higher capacity and average velocity and smaller hydrogen pressure and hysteresis coefficient of hydrogen absorption and desorption.Based on comprehensive comparison,the suitable annealing temperature is 950 ℃for the alloy in our experiments.