纳米晶(Ag-Cu28)-25Sn合金粉末的制备及表征

采用机械合金化法制备纳米晶(Ag-Cu28)-25Sn合金粉末.用X射线衍射(XRD)仪、扫描电镜(SEM)、高分辨透射电镜(HRTEM)和差示扫描量热分析仪(DSC)等分析手段,对合金化过程中物相组成、微观结构及熔化特性进行表征.结果表明:(Ag-Cu28)-25Sn纳米晶合金粉末的物相组成为Cu3Sn和Ag4Sn.球磨 40 h,合金化完全,其熔化温度为548.5 ℃;球磨至60 h,合金明显非晶化,其熔化温度为554.0 ℃,熔程变小且在186.3和399.5 ℃处出现明显放热峰.HRTEM表明,纳米晶的尺寸约为5～10 nm,合金中有非晶态物质出现和晶格缺陷产生.200和400 ℃退火后,合金的平均晶粒尺寸分别为21.3和33.9 nm.

Preparation and Characterization of Nanocrystalline (Ag-Cu28)-25Sn Alloy Powder

Nanocrystalline (Ag-Cu28)-25Sn alloy powder was prepared by mechanical alloying (MA). The phase composition, microstructure and melting properties of the as-milled alloy powder were studied by XRD, SEM, HRTEM and DSC. The results show that the phase composition of nanocrystalline (Ag-Cu28)-25Sn alloy powder is Cu3Sn and Ag4Sn phase. After milled for 40 h, the alloying process is completed and the melting temperature of the as-prepared alloys is 548.5 oC. With the milling time increasing to 60 h, the alloy becomes amorphous obviously whose melting temperature is 554.0 oC. The melting zone reduces and there are two clear exothermic peaks at 186.3 oC and 399.5 oC in DSC curve. Moreover the HRTEM result indicates that the nanocrystalline size is from 5 nm to 10 nm and there are amorphous phases and lattice defects in alloying process. The average grain sizes of as-prepared alloys annealed at 200 oC and at 400 oC are 21.3 nm and 33.9 nm, respectively.