La_(0.75)Mg_(0.25)Ni_(3.1-x)Co_(0.4)Al_x合金的微观结构及性能

Microstructure and performance of La_(0.75)Mg_(0.25)Ni_(3.1-x)Co_(0.4)Al_x alloys

通过铸造工艺制备La0.75Mg0.25Ni3.1-xCo0.4Alx(x=0、0.05、0.10、0.15和0.20)贮氢合金,并对x=0.10的合金进行退火处理。分析了Al替代量x和退火温度对合金的影响。合金均含有(La,Mg)Ni3相(PuNi3结构)、LaNi5相和一定量的LaNi2相。铸态合金中LaNi5相的量由x=0时的14.28%增至x=0.20时的24.07%。Al的替代提高了合金的循环稳定性,但比容量由x=0时的398.7mAh/g降至x=0.20时的350.1mAh/g。合金均有优良的活化性能。在900℃下的退火处理,使合金的容量和循环稳定性得到提高。

La0.75Mg0.25Ni3.1-xCo0.4Alx（x=0,0.05,0.10,0.15 and 0.20）hydrogen storage alloys were prepared by casting and annealing treatment was performed on the（x=0.10）alloy. The effects of Al substitution amount（x）and annealing temperature to the alloys were researched. The alloys had（La,Mg）Ni3 phase（PuNi3 structure）,LaNi5 phase and some LaNi2 phase. The amount of LaNi5 phase in the as-cast alloys increased from 14.28%（x=0）to 24.07%（x=0.20）. The substitution of Al enhanced the cycle stability of the alloys,but the specific capacity decreased from 398.7 mAh/g（x=0）to 350.1 mAh/g（x=0.20）. The activation behavior of the alloys was fine. The capacity and cycle stability of the alloy were improved by annealing treatment at 900 ℃.