本研究利用熔煉法製備Mg1-xNix(X=5-35 wt％)合金，觀察合金微結構變化對儲放氫特性之影響。經PCI測試發現，過共晶合金較亞共晶合金易達理論吸氫量。由過共晶微結構可知，其為初晶Mg2Ni與共晶層狀(Mg＋Mg2Ni)所組成，亞共晶為初晶Mg與共晶結構。亞共晶合金中，初晶Mg面積大與Mg2Ni接觸面積少較不易受Mg2Ni的催化，過共晶合金中不僅Mg與Mg2Ni的界面多，Mg2Ni也較多，相界為氫原子擴散之途徑，故吸氫速率快，吸氫量也較易達理論值。共晶合金為Mg與Mg2Ni層狀結構，具有最多之界面，Mg2Ni更易催化Mg，導致共晶合金之吸氫速率與吸氫量皆有極佳的表現。而藉由球磨可減小合金粉末顆粒，增加缺陷與比表面積，致使合金更易活化。但於PCI測試中發現，球磨合金中Mg與Mg2Ni的平台長度相較於鑄態合金皆有減少的現象，推測因鋼球的撞擊導致延性較佳之Mg包覆Mg2Ni，以致Mg難以受Mg2Ni催化，降低合金吸氫量與吸氫速率。

This research plans to utilize casting method to prepare Mg1-xNix (x= 5、10、15、23.5、35 wt%) , and then studies the effect of Mg2Ni catalyst on Mg of hydrogen storage characteristic with different microstructure. The hypereutectic alloy consists of primary Mg2Ni and eutectic (Mg+Mg2Ni). The microstructure of hypoeutectic alloy is primary Mg and eutectic (Mg+Mg2Ni). The eutectic (Mg+Mg2Ni) structure is lamella-type layer. After PCI test, we observe that the hydrogen capacity of hypereutectic alloy and eutectic alloy are easy getting the theoretic hydrogen capacity. Because the contact area of Mg and Mg2Ni to hypereutectic alloy and eutectic alloy are larger than hypoeutectic alloy,Mg2Ni catalyzes Mg more effectively. The larger primary Mg of hypoeutectic alloy which can not be catalyzed by Mg2Ni easily. And the phase boundaries of Mg and Mg2Ni are diffusion path of hydrogen atom so eutectic alloy has the best capability for hydrogen capacity and absorption rate. After ball milling, the alloys increase the defects and surface area which make alloys activate more easily. But we observe that the Mg and Mg2Ni plateau length of PCI curves are reduced after ball milling. It presumes that the more brittle Mg2Ni is embedded into the more ductile Ni powders. The hydrogen capacity and absorption rate are reduced after ball milling.

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