储氚合金ZrCo0.8M0.2 (M = Co, Cu, Cr, Mn, Al)的性能研究

Study of the properties of ZrCo0.8M0.2 (M = Co, Cu, Cr, Mn, Al) alloys for tritium storage

摘要:

采用电弧熔炼的方法在氩气气氛中熔炼了ZrCo_0.8M_0.2 (M = Co、Cu、Cr、Mn、Al)合金。合金的主相均为ZrCo相,但Cr、Mn和Al部分替代Co后形成了第二相。Cr替代形成了Zr₂Co和ZrCr₂相,Mn替代形成了Zr₂Co和ZrMn₂相,Al替代形成Zr₃Co和Zr₆CoAl₂相。Cr和Mn的替代使合金的晶胞体积减小,而Cu和Al的替代使晶胞体积增大。Cu、Cr、Mn和Al替代后,ZrCo_0.8M_0.2合金的平台压变化不明显,但吸氢量出现了不同程度的降低。Cr和Mn元素的替代明显改善了ZrCo合金在室温下的活化性能。Cr和Mn元素的替代降低了高温下ZrCo合金发生歧化反应的速率,这主要是由于Cr和Mn元素的掺杂减少了氢原子占据不稳定位置8f₂ 和8e的数量,从而降低了歧化反应发生的驱动力。

Abstract:

ZrCo_0.8M_0.2 (M = Co, Cu, Cr, Mn, and Al) alloys were prepared via the arc melting method in an argon atmosphere. The major phase of the alloys arranges itself in a ZrCo structure. The partial addition of Cr, Mn, and Al leads to the formation of a secondary phase. The Zr₂Co and ZrCr₂ phases, the Zr₂Co and ZrMn₂ phases, and the Zr₃Co and Zr₆CoAl₂ phases are formed upon Cr, Mn, and Al substitution, respectively. The cell volume of the alloys decreases upon Cr and Mn substitution, and increases upon Cu and Al replacement. Moreover, the hydrogen storage capacity of the alloys decreases when Cu, Cr, Mn, or Al are present in the alloy. However, the plateau of the desorption pressure remains nearly unchanged for all the alloys. The ZrCo alloy activation performance drastically improves upon Cr and Mn addition at room temperature, while the disproportionation reaction rate decreases, due to the decrease in its driving force. A modification of the 8f₂ and 8e sites results in a change in the disproportionation driving force in all the investigated alloys.