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采用X射线衍射仪、金相显微镜和扫描电镜,研究了Ag-Sn-La合金粉末的氧化组织。结果表明:Ag-Sn-La系合金粉末氧化后主要由Ag、SnO2和La2Sn2O73种相组成;合金元素含量不同,Ag-Sn-La合金粉末具有不同的氧化动力学特征、氧化组织和氧化机制。Ag-5.2Sn-3.4La合金粉末的起始氧化温度为350℃,氧化速度较快,元素La和Sn发生原位氧化,但柱状晶上La的快速优先氧化使得合金内部出现条状的氧化物;Ag-6.87Sn-1.28La合金粉末从加热一开始便发生缓慢氧化,在300℃以后开始快速氧化,元素La和Sn发生原位氧化,原位生成的氧化物颗粒弥散分布在银基体上;Ag-9.26Sn-0.44La合金粉末的起始氧化温度为567℃且氧化速度较慢,元素La发生原位氧化,而部分Sn在浓度梯度的驱动下向外扩散,生成的氧化锡颗粒主要分布在粉末边界,而La的氧化物则弥散分布在银基体上。
The oxidation structure of Ag-Sn-La alloy powders was investigated by X-ray diffraction, optical microscope and scanning electron microscope. The results show that Ag-Sn-La alloy powders mainly consist of Ag, SnO2 and La2Sn2O73 phases after oxidation. Different oxidation kinetics, oxidation mechanism and oxidation mechanism of Ag-Sn-La alloy powders are different. The initial oxidation temperature of Ag-5.2Sn-3.4La alloy powder is 350 ℃, the oxidation rate is faster, the elements La and Sn are in situ oxidized, but the rapid preferential oxidation of La on the columnar crystal leads to the appearance of bar oxide ; The Ag-6.87Sn-1.28La alloy powder slowly oxidized from the beginning of the heating, rapid oxidation started after 300 ℃, the elements La and Sn were oxidized in situ, the in-situ oxide particles dispersedly distributed on the silver matrix; Ag-9.26Sn-0.44La alloy powder has an initial oxidation temperature of 567 ℃ and a slow oxidation rate, and the elemental La undergoes in-situ oxidation while part of Sn diffuses outwards under the concentration gradient. The resulting tin oxide particles are mainly distributed At the powder boundary, La’s oxide is diffusely distributed on the silver matrix.