Nb含量对机械合金化Cu-Nb合金晶粒细化和力学性能的影响（英文）

Effect of Nb Solute Concentration on Crystallite Size Refinement and Strength Enhancement in Mechanically Alloyed Cu-Nb Alloys

采用机械合金化法制备了质量分数x=0%～30%的Cu-xNb合金粉末,通过X射线衍射仪(XRD)、金相显微镜(OM)、扫描电镜(SEM)、透射电镜(TEM)观察和显微硬度测量分析了Nb溶质含量对粉末晶粒细化过程以及力学性能的影响。结果表明,尽管Nb与Cu的平衡固溶度接近为0,经100 h球磨后,Nb在Cu中的最大固溶量可达约11%。随着Nb含量的增加,Cu-Nb合金粉末的晶粒细化能力提高。这是由于随着偏析至位错处的溶质原子数量增加,合金的回复过程得到抑制,因此有利于晶粒尺寸的减小。Cu-30%Nb合金球磨100 h后Cu相平均晶粒尺寸减小至约6 nm。此外,球磨Cu-Nb合金粉末的显微硬度随着Nb含量的增加而提高,其强化机制主要为细晶强化和固溶强化。

Cu-Nb alloys with a Nb concentration range of 0 wt%～30 wt% were prepared by mechanical alloying（MA） at room temperature.The effects of Nb content on the crystalline refinement process and mechanical properties of the immiscible Cu-Nb system were investigated by X-ray diffraction（XRD）,optical microscopy（OM）,scanning electron microscopy（SEM） with energy-dispersive X-ray detection（EDX）,transmission electron microscopy（TEM） and microhardness measurement.Results show that the completed dissolution of Nb in Cu can be achieved in the samples with Nb content less than ~11 wt% after 100 h milling,although the equilibrium solubility level is nearly zero.The grain size refinement capability of MA-ed Cu-Nb powder is enhanced with increasing Nb content up to 30 wt%.This is because the susceptibility to recovery process becomes reduced,when the amount of Nb solutes segregated into the dislocation of Cu phase is increased.Cu-30 wt%Nb powder milled for 100 h,the average Cu grain size is only ~6 nm.The microhardness of the samples shows an enhancement with increasing Nb concentration.The main strengthening mechanisms of the MA-ed Cu-Nb alloys are linked to the grain size reduction and the dissolution of Nb into Cu matrix.