薄壁铸造和退火工艺对LPCNi3.55Co0.75Mn0.4Al0.3贮氢合金电化学性能的影响

研究了不同铸锭厚度(1～10mm)对薄壁铸造的铸态和退火态LPCNi3．55Co0.75Mn0.4Al0.3贮氢合金电化学性能的影响。结果发现：铸态LPCNi3．55Co0.75Mn0.4Al0.3合金的0．2C放电容量随着合金锭厚度的增加有增大的趋势。10mm厚铸态合金的活化性能优于其它厚度的合金，且在1C的放电容量和循环稳定性比在其它厚度的高。主要原因应归结为该厚度合金具有更大的晶胞体积和更小的晶格应力。退火态3mm LPCNi3．55Co0.75Mn0.4Al0.3合金的综合电化学性能比铸态更优异，6mm合金的循环稳定性和3～6mm合金的活化性能得到改善。主要原因应归结为晶格应力的极大释放以及Mn等元素偏析的改善。

Effect of Strip Casting and Annealing on Electrochemical Properties of LPCNi3.55Co0.75Mn0.4Al0.3 Hydrogen Storage Alloys

The effect of thickness (1 - 10 mm) of the ingots on the electrochemical properties of as-cast and annealed strip cast LPCNi3.55Co0.75Mn0.4Al0.3 hydrogen storage alloy was discussed. It is found that the 0. 2C discharge capacity of as-cast LPCNi3.55Co0.75Mn0.4 Al0.3 alloy tends to increase with the increase of the thickness of the ingots. 10 mm as-cast alloy shows better activation property, higher 1C discharge capacity and better cyclic stability than others. This is main- ly contributed to larger unit cell volume and less internal stress in this alloy with 10 mm. Annealed 3 mm LPCNi3.55Co0.75 Mn0.4 Al0.3 alloy shows much better comprehensive electrochemical properties than as-cast one. The cyclic stability of 6 mm one and the activation property of 3 - 6 mm ones are improved. This is mainly owing to the great release of internal stress and the decease of the segregation of Mn.