球磨工艺对SPS烧结Mo-5%Ta合金靶材性能的影响

Effect of Ball Milling Processes on Properties of Mo-5%Ta Alloy Targets Sintered by SPS

采用球磨和放电等离子烧结(SPS)工艺制备了Mo-5%Ta(质量分数,下同)混合粉末及其合金,研究了不同球磨工艺对粉末形貌、粒度及烧结后合金微观结构、硬度及热导率的影响。结果表明:球磨时间和球磨转速均不同程度的改变了原始粉末的团聚现象,但低转速(150 r/min)球磨对粉末形貌的影响相对较小。随着球磨时间的增加,Mo-5%Ta粉末粒度先增大后减小,而随着球磨转速的增加,Mo-5%Ta粉末粒度先减小后增大。球磨后的Mo-5%Ta粉末经SPS烧结所得合金的组织细小均匀,随着球磨时间、球磨转速的增加,合金晶粒尺寸减小,相对密度先增加后降低,维氏硬度(HV0.5)增大,热导率(25℃)无明显变化。当球磨时间为20 h、球磨转速为300 r/min时,烧结样品的相对密度达到99.19%、晶粒尺寸为5.73μm、维氏硬度(HV0.5)为241.67及热导率(25℃)为159.34 W/(m·K)。

In this paper,the mixed powders of Mo-5%Ta(mass fraction,the same below)and its alloys were prepared by ball milling and spark plasma sintering(SPS).We studied the effects of different ball milling processes on the morphology and particle size of the powders as well as the microstructure,hardness,and thermal conductivity of the sintered alloys.The results reveal that both the time and speed of ball milling change the agglomeration phenomenon of original powders to different degrees,but the effect of low speed(150 r/min)on the powder morphology is marginal.With the increase in ball milling time,the particle size of Mo-5%Ta powders first increases and then decreases,while with the increase in ball milling speed,the particle size of Mo-5% Ta powders drops before it rises.The structures of the Mo-5% Ta samples sintered by SPS after ball milling are fine and uniform.With the increase in time and speed of ball milling,the alloys have smaller grain size,larger Vickers hardness(HV0.5),and basically invariant thermal conductivity(25℃),with the density increasing before declining.The comprehensive analysis demonstrates that the sintered samples register a density of 99.19%,a grain size of 5.73μm,the Vickers hardness(HV0.5)of 241.67,and the thermal conductivity(25℃)of159.34 W/(m·K)when the ball milling is performed for 20 h at the speed of 300 r/min.