(1. 昆明理工大學 材料科學與工程學院，昆明 650093；
2. 昆明貴金屬研究所，昆明 650106)
摘 要: 采用 X 射線衍射儀(XRD)和電子探針顯微分析儀(EPMA)等方法測定了Au-Pt-Sn 三元系 700 ℃等溫截面。結果表明：Au-Pt-Sn 體系 700 ℃等溫截面由3個單相區(qū)、7個兩相區(qū)和6個三相區(qū)組成。6個三相區(qū)分別為Pt3Sn+FCC-A1+PtSn、PtSn+FCC-A1+Au5Sn、PtSn+Pt3Sn+Au5Sn、Pt3Sn+FCC-A1+Au5Sn、PtSn+Pt2Sn3+Liquid和PtSn+FCC-A1+Liquid。Au-Pt-Sn體系中存在Au-Pt合金的調幅分解反應，隨著Pt含量的減少，合金中調幅分解相逐漸消失，在Au16Pt30Sn54和Au16Pt20Sn64合金中完全消失。由于Pt-Sn合金相的熔點較Au-Sn合金的相高，所以在700 ℃等溫截面，大都只存在Pt-Sn合金相，而Au-Sn合金相大都只存在于液相中。合金Au16Pt69Sn15、Au16Pt54Sn30和Au16Pt42Sn42由于存在調幅分解相，組織分布較均勻，其強度明顯比合金Au16Pt30Sn54和Au16Pt20Sn64的高。
關鍵字: Au-Pt-Sn 體系；相圖；等溫截面；顯微組織；相平衡；調幅分解
（1. School of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093, China;
2. Kunming Institute of Precious Metals, Kunming 650106, China）
Abstract:The isothermal section of the Au-Pt-Sn ternary system at 700 ℃ was investigated by X-ray diffractometer and electron probe microanalyzer. The results show that the isothermal section of the Au-Pt-Sn ternary system at 700 ℃ is composed of three single-phase regions, seven two-phase regions and six three-phase regions. The six three-phase regions including Pt3Sn+FCC-A1+PtSn, PtSn+FCC-A1+Au5Sn, PtSn+Pt3Sn+Au5Sn, Pt3Sn+FCC-A1+Au5Sn, PtSn+Pt2Sn3+Liquid, PtSn+FCC-A1+Liquid. The spinodal decomposition reaction of Au-Pt alloy exists in the Au-Pt-Sn system. With decreasing Pt content, the spinodal decomposition phase in the alloy gradually disappears, and it completely disappears in Au16Pt30Sn54 and Au16Pt20Sn64 samples. Because the melting point of Pt-Sn alloy phase is higher than that of Au-Sn alloy, most of phases in 700 ℃ isothermal section are Pt-Sn alloy, while Au-Sn alloy phase mainly exists in liquid phase. The microstructures distribution of Au16Pt69Sn15, Au16Pt54Sn30 and Au16Pt42Sn42 alloy are more uniform and the strengths of the alloy are higher than that of Au16Pt30Sn54 and Au16Pt20Sn64 alloy because of the existence of spinodal decomposition phase.
Key words: Au-Pt-Sn system; phase diagram; isothermal section; microstructure; phase equilibrium; spinodal decomposition
