高能球磨-放电等离子烧结法制备双晶分布钛

以平均粒径约150μm的球形钛粉为原料,采用高能球磨结合放电等离子烧结技术制备由双尺度晶粒组成的高致密纯钛块体材料,研究高能球磨过程中钛粉的形貌、尺寸及显微组织的变化,分析球磨钛粉放电等离子烧结时的致密化行为和显微组织的演变规律,测试烧结钛块体材料的室温压缩性能。结果表明:钛粉在球磨初期发生剧烈的塑性变形并相互焊合,形成层片状团聚粉末。球磨10 h时,钛粉的部分晶粒细化至40~100 nm。放电等离子烧结过程中,随烧结温度升高和烧结时间延长,烧结钛的密度逐渐增大。在烧结温度为800℃、保温时间为4 min、烧结压力为50 MPa的条件下,烧结钛的密度达到4.489 g/cm3,接近全致密,其显微组织由双尺度的等轴晶组成,细晶区晶粒尺寸为1~2μm,粗晶区晶粒尺寸为5~20μm,二者呈层状交替分布;该试样在室温压缩条件下的综合力学性能与铸锻Ti-6Al-4V合金相当。

Fabrication of bimodal-microstructured Ti by spark plasma sintering of high-energy ball-milled powders

Using the spherical titanium powders with a mean size of 150 μm as the raw material,high-density bimodal-microstructured pure titanium bulk material was produced by high-energy ball-milling and subsequent spark plasma sintering(SPS).The morphology,particle size and microstructure of ball-milled titanium powders were studied.The densification behavior and microstructure evolution during spark plasma sintering process of ball-milled titanium powders were analyzed.The mechanical properties of sintered samples were investigated.Experimental results show that agglomerate particles comprizing layers of original titanium powders are formed at the early stage of ball-milling because of heavy deformation and cold welding.The grain size of titanium powders is decreased to 40~100 nm when the ball-milling time is 10 h.The density of the sintered titanium increases with the sintering temperature and the holding time of the SPS process.When the sintering temperature,holding time and sintering pressure is 800 ℃,4 min and 50 MPa,respectively,the density of sintered sample reaches 4.489 g/cm3,which is nearly the theoretical density of titanium,and the sintered titanium shows a laminated microstructure consisting of coarse grained region and fine grained region.The grain size of fine grained region is 1~2 μm,and the grain size of coarse grained region is 5~20 μm.The compressive mechanical property at room temperature of the sintered sample is comparable with the casting-forging Ti-6Al-4V alloy.