AgSn合金粉体粒度对预氧化显微组织的影响

Effect of Particle Size of AgSn Alloy Powders on Pre-oxidation Microstructure

考察了粒度分别为15、116、264μm的AgSn合金粉体对预氧化组织的影响,并比较了15μm和264μm粉体经预氧化挤压后的性能和显微组织。结果表明,粉体粒度为15μm时,氧化主要发生在颗粒边缘,随着粒度增加,颗粒周围形成了氧化层,甚至出现了氧化物聚集;15μm粉体挤压后氧化物颗粒分布均匀,而264μm雾化粉挤压后存在明显的氧化物富集区和贫氧化物区,导致后者的硬度、延伸率略低于前者;较大粒度的AgSn粉体(116μm和264μm)出现氧化层的原因是氧化物膜层松动或开裂,氧化层中出现了合金成分,反应又进入快速反应阶段,形成了一层氧化物层。

Effects of different particle size of AgSn alloy powders（15 grn, ll6 gm,264 gm respectively） on pre-oxidation microstrucure were investigated. Besides, properties and microstructure of the powders of 15 gm and 264 ~tm after extrusion were compared. It is shown that oxidation mainly occures at the edge of the particles when the particle size is 15 pro. The oxide layer forms around the particles as the particle size increases, even oxide aggregates appeares when the particle size increases to 264 Ixm. After extrusion, oxide particles distribute uniformly when the particle size is 15 gin, while the obvious oxide-rich and oxide-depleted zones are observed as the powder size increases to 264 gm. As a result, hardness and elongation of the latter one are slightly lower than the former one. When the particle size is more than 116 pro, the oxide film maybe loose or cracks appeare in the oxide film during the internal oxidation stage, thus rapid reaction will take place and oxide layer is formed.