双步球磨与放电等离子烧结制备细晶TiAl合金

采用双步球磨法和放电等离子烧结(SPS)技术制备细晶Ti-47Al(at%)合金,利用扫描电子显微镜(SEM)、X射线衍射(XRD)仪以及透射电子显微镜(TEM)等分析测试手段对球磨后的粉末形貌结构、相组成以及烧结块体的显微组织结构进行观察和分析。结果表明:双步球磨粉末的颗粒形状较规则,其颗粒尺寸在20~40μm之间,内部结构均匀,主要由TiAl和Ti3Al相组成。放电等离子烧结后的块体主要由主相TiAl和少量的Ti3Al相及Ti2Al相组成,随着烧结温度的升高,Ti3Al相含量有所增加。当烧结温度为1000℃时,烧结块体获得的主要是等轴晶组织,等轴晶粒尺寸大多数在100~250nm之间。当烧结温度为1100℃时,烧结块体致密、无孔洞,等轴晶粒有明显长大的现象,显微组织主要由等轴状的TiAl相和片层状的Ti3Al相组成。

Fine-Grained TiAl Alloy Prepared by Double Mechanical Milling and Spark Plasma Sintering

Fine-grained Ti-47Al(at%) alloy was prepared by double mechanical milling and spark plasma sintering(SPS).The morphology,microstructure and phase composition of the Ti-47Al composite powder and the microstructure of the bulk Ti-47Al alloy samples were studied by SEM,XRD and TEM.The results show that the double mechanical milled powder is composed of TiAl and Ti3Al phases,with regular particle shape and 20-40 μm particle size,as well as uniform interstructure.The SPSed bulk of Ti-47Al alloy consists of main phase TiAl and few phases Ti3Al and Ti2Al.With the sintering temperature increasing,the Ti3Al phase becomes more.For the bulk sintered at 1000 oC,the equiaxed grain microstructure is achieved with sizes in the range of 100-250 nm.For the bulk sintered at 1100 oC,the sizes of equiaxed grain significantly are increased.The SPSed bulk samples exhibit dense microstructure without pores,consisting of equiaxed TiAl phase and lamellar Ti3Al phase.