等离子旋转电极法制备钛铝粉末性能表征

Characterization of TiAl Powders Prepared by Plasma Rotating Electrode Processing

采用等离子束旋转电极法制备Ti-47Al-2Cr-2Nb球形粉末,粉末的平均粒径d50为85μm,松装密度为2.65g/cm3。截线法测得粉末的球形度为99.6%;粉末的流动性为10.40s/50g;粉末的平均氧、氮含量分别为0.05%和0.004%。XRD分析表明,粉末的相组成为α2相和γ相,主相为富钛α2相;粉末经热等静压后主相为γ相,伴随少量α2相。SEM背散射照片表明,粉末颗粒的晶粒为胞状组织,晶粒平均大小约为2μm;对不同粒径的颗粒进行EPMA分析表明,颗粒内部化学成分与预合金棒接近,颗粒表面有部分Al元素挥发,约为2at%。

Ti-47Al-2Cr-2Nb Spherical powders were fabricated directly from the master electrode by the plasma rotating electrode processing (PREP) and the products were analyzed by XRD, SEM, EPMA etc. The average particle size d(50) of the powder is 85 mu m, the loose density is 2.65 g/cm(3), the flowability is 10.40 s/50 g, and the sphericity is 99.6% tested via a line transversal method. The mean content of oxygen and nitrogen is 0.05% and 0.004%, respectively. XRD patterns indicate that the obtained powders consist of Ti-rich alpha(2)-Ti(3)Al and a few gamma-TiAl phases, while for the as-HIPed sample the main phase is gamma phase with a few alpha(2) phase. SEM images with back scattered mode analysis show that the grains of the powder particles are of cellular structure with average size of about 2 mu m. EMPA test for a series of different diameters powders indicates that the chemical composition in center is closed to that of prealloyed rod, except the surface of the powder where the evaporation of Al is about 2at%.