La0.75Mg0.25Ni3.1-xCo0.4Alx合金的微观结构及性能

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。

Microstructure and performance of La0.75Mg0.25Ni3.1-xCo0.4Alx alloys

La0.75Mg0.25Ni3.1-xCo0.4Alx(x=0,0.05,0.10,0.15 and0.20)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 arhount 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℃.