Si元素含量对激光快速成形制备Nb-Si二元合金显微组织演变的影响  

Effect of Si content on microstructural evolution of Nb-Si binary alloys fabricated by laser rapid forming

作　　者：刘伟[1] 熊华平[1] 唐思熠[1] 

机构地区：[1]北京航空材料研究院焊接与塑性成形研究所,北京100095

出　　处：《焊接学报》2017年第3期53-56,61,共5页Transactions of The China Welding Institution

基　　金：国家自然科学基金青年科学基金资助项目(51605456)

摘　　要：以铌粉和硅粉为原料,采用双通道同轴送粉制备了四种不同Si元素含量的Nb-Si二元合金,通过扫描电镜(SEM)、能谱仪(EDS)及X射线衍射仪(XRD)等分析了合金的显微组织演变及维氏硬度.结果表明,硅含量由7%增加至25%,合金的显微组织由Nb_(SS)+Nb_3Si转变为初生Nb_(SS)+(Nb_(SS)/Nb_3Si)共晶,硅含量为18%时,呈Nb_(SS)/Nb_3Si全共晶组织,硅含量提高至25%,合金中出现初生β-Nb_5Si_3相,并仍存在Nb_(SS)/Nb_3Si共晶组织.铌和硅粉末在激光作用下原位反应并快速凝固,显著细化了Nb-Si合金的显微组织.随硅含量增加,硅化物含量逐渐增加,合金显微硬度由746 HV增至1 342 HV.The high purity Nb powder and Si powder were used as raw powder and four kinds of Nb-Si binary alloys with different Si content were fabricated by laser rapid forming with double coaxial powder feeding.The microstructural evolution and the micro-hardness of these alloys were investigated by scanning electron microscope(SEM),X-ray energy dispersive spectroscopy(EDS)and X-ray diffraction spectrometer(XRD).The results showed that with the content of Si increasing from 7% to 25%,the microstructure of Nb-Si binary alloys was changed from NbSS+Nb3 Si to primary NbSS +(NbSS/Nb3Si) eutectic structure.When the content of Si was 18%,the fabricated alloy is almost 100% NbSS/Nb3 Si eutectic structure.With the Si content reaching 25%,the primaryβ-Nb5Si3 phase appears and the NbSS/Nb3 Si eutectic structure still existed.Moreover,under the high energy of laser beam,the in situ reaction between Nb and Si powder would occur and the microstructure of Nb-Si alloys could be refined significantly.With the content of Si increasing,the volume fraction of silicide increased gradually and the micro-hardness of the alloys increased from 746 HV to1 342 HV.

关 键 词：Nb-Si二元合金 激光快速成形 显微组织 显微硬度 硅含量 

分 类 号：TG456[金属学及工艺—焊接]