| The alloying behaviors of silver, corrosion behaviors and protective measurements of silver and its alloys, and development of sterling silvers have been summarized in the thesis. Based on the above work, nine sterling silvers were arc-melted with a non-consumable electrode and water-cooled copper crucible under an argon atmosphere, and the effects of alloying elements of Zn, Sn and In on microstructure, microhardness, corrosion behaviors in artificial sweat and H2S atmosphere of sterling silver in various heat-treated states have been investigated, in order to supply some theoretic references for composition and heat treatment process designs of sterling silvers with good overall properties, by means of microhardness test, optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), transmission electron microscopy (TEM), X-Raydiffraction analysis (XRD), differential scanning calorimetry (DSC), X-Ray photoelectrical spectrometry (XPS), static immersion test and potentiodynamic polarization analysis in artificial sweat at 37℃as well as exposure test in H2S atmosphere at 25℃. Adding 2.53.5wt% Zn to conventional sterling silver, namely Ag92.5Cu7.5 alloy, reduced porosity of as-cast microstructure significantly, and induced grains refining, but induced grains coarsening during subsequent heat treatment. During aging at the temperature between 200℃and 350℃, convex microstructure appeared as well as rich-Cu phase. These sterling silvers also possess good aging strengthening effect, for example, for Ag92.5Cu4.0Zn3.5 alloy, after aging at 250℃for 4h, its microhardness reached 124.4HV0.2, which is 1.95 times of its solutionized microhardness 63.8HV0.2. Compared with Ag92.5Cu7.5 alloy, corrosion rate are lower, and color stability are better in artificial sweat at 37℃because grey-black corrosion products come into being more difficultly. In addition, sulphuration resistance against discoloration into black of these alloys are better in H2S atmosphere at 25℃.Further adding 1.0wt% Sn, 2.0wt% In, or 1.0wt% Sn and 0.4wt% In to replace part of Zn in Ag92.5Cu4.0Zn3.5 alloy, as-cast microstructures of these sterling silvers are still dense, and microstructure evolutions don't changed during subsequent heat treatment. These sterling silvers also possess good aging strengthening effect, for example, for Ag92.5Cu4.0Zn2.1Sn1.0In0.4 alloy, after aging at 150℃for 4h, its microhardness reached 127.2HV0.2, which is 2.20 times of its solutionized microhardness 57.9HV0.2. Moreover, the microhardness and color stability of these alloys in artificial sweat at 37℃are not inferior to those of Ag92.5Cu4.0Zn3.5 alloy, and the sulphuration resistance against discoloration into black is better in H2S atmosphere at 25℃.
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