A spherical Fe matrix composite powder containing a high volume fraction(82vol%) of fine TiC reinforcement was produced using a novel process combining in situ synthesis and plasma techniques. The composite powder exhibited good sphericity and a dense structure, and the fine sub-micron TiC particles were homogeneously distributed in the α-Fe matrix. A TiC –Fe cermet was prepared from the as-prepared spherical composite powder using powder metallurgy at a low sintering temperature; the product exhibited a hardness of HRA 88.5 and a flexural strength of 1360 MPa. The grain size of the fine-grained TiC and special surface structure of the spherical powder played the key roles in the fabrication process.
Spherical tungsten and titanium powders were prepared by radio frequency inductively coupled plasma torch with irregular shaped tungsten and titanium hydride(Ti H_2) powders, respectively. The effect of the feed rate on spheroidization efficiency was investigated. The phase composition, oxygen content, morphology, and particle size distribution of the powders before and after spheroidization were characterized by X-ray diffraction(XRD),nitrogen/oxygen analyzer, scanning electron microscopy(SEM), and laser micron sizer(LMS). The results show that both kinds of plasma-processed powders have good dispersity, smooth surface, and single phase. A maximum of 100 % of spheroidization efficiency can be achieved at a lower feed rate. The spherical titanium powder obtained by the plasma treatment consists of particles with mean diameter of 33.34 lm, while the mean diameter of original Ti H_2 powder is 136.56 lm. The apparent density and flowability of the spherical tungsten powder are 6.3 g·cm^(-3) and 0.16 s·g^(-1), respectively. The apparent density and flowability of the spherical titanium powder are 2.8 g·cm^(-3) and 0.52 s·g^(-1), respectively. With the increase of the feed rate, the spheroidization efficiency of raw powders drops gradually.
