中文摘要：

采用液相还原法，随后在620℃、58MPa下经真空热压，制备了纳米晶Ag-50Ni块体合金，并通过X射线衍射（XRD）仪、扫描电镜（SEM／EDX）和透射电镜（TEM）研究了其显微组织结构。结果表明，Ag-Ni粉末的最佳合成工艺条件为：反应体系温度为70℃；还原剂水合肼（N2H4·H2O）浓度为2．5mol·L^-1：反应物AgNO3浓度为1.5mol·L^-1；反应物NiSO4的浓度为1．5mol·L^-1；反应体系pH值为8。Ag-Ni粉末平均粒度约为45nm，黑色无定形形状。Ag-Ni粉末经真空热压后，晶粒尺寸有所长大，但仍保持纳米级尺度。合金致密度很高，由双相组成，显微组织均匀且无Ag网出现。

英文摘要：

A nanocrystalline Ag-50Ni bulk alloy has been prepared by hot pressing powders obtained by aqueous reducing method at 620℃ under a normal ＇pressure of 58 MPa. The microstructural characteristics of the sample were studied by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. The results show that the optimal processing parameters are as follows： the temperature of reaction system 70℃, the concentration of reactant AgNO3 1.5 mol·L^-1, the concentration of reactant NiSO4 1.5 mol·L^-1, the concentration ofreductant hydrazine hydrate 2.5 mol·L^-1, pH value of reaction system 8. Ag-Ni powder is black and amorphous solid. Its average particle size is about 45 nm. The sizes increase slightly but still remain in nano-size range after hot pressing. The alloy is composed of two-phases and has high density. Its microstructure is homogeneous and has no Ag net.