利用球磨和热压致密化过程，得到富Ag和富Ni相均匀分布的 纳 米晶Ni-Ag双相合金.研究了含Ni分别为50 at%和75 at%的Ni-50Ag和Ni-25Ag合金在600～70 0℃空气中的氧化.Ni-50Ag合金形成了Ni内氧化结构，最外层为连续Ag层，其氧化速率 大于纯Ni.相反，Ni-25Ag合金则形成了连续的NiO外氧化层且最外层为不连续的Ag层.Ni-25A g合金氧化初期服从抛物线速率常数关系，随后氧化速率显著减小甚至小于纯Ni.合金的双相 结构特性以及合金中极小的晶粒尺寸导致了上述结果的产生.
Two Ni-Ag alloys, containing Ni of 50 at% and 75 at %, denoted as Ni-50Ag and Ni-25Ag were consolidated with hot pressing (HP) proce ssing after mechanical alloying (MA) for 80 hr. The nanocrystalline alloys have been oxidized in air at 600-700 ℃ for 24 hr.Ni-50Ag alloy undergoes an inte rna l oxidation of nickel associated with the formation of a continuous outermost la yer of silver metal and has oxidation rates larger than those of pure nickel. On the contrary, Ni-25Ag alloy forms a continuous NiO layer surmounted by a discon tinuous silver layer, while the internal oxidation is suppressed. These results are interpreted on the basis of the two-phase nature of the alloys and of their particularly small grain size.
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