Effects of mechanical alloying on characteristics of nanocrystalline Fe–Cr–W–Ti–Y2O3 powders

Effects of mechanical alloying (MA) parameters on characteristics of nanocrystalline Fe–Cr–W–Ti–Y2O3 powders, including alloying degree, grain size, microhardness and morphology had been systematically investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that the alloying degree of milled powders was increased with the elevation of milling rotational speed and elongation of milling duration. The W atoms were completely dissolved into the iron matrix after milling at 350 rpm for 24 h. The grain size of milled powders was decreased sharply at first stage of milling and leveled off after 24 h, while lattice strain was increased. The microhardness of alloyed powders was elevated firstly and stabilized at about 607.4 HV after 24 h milling. Process control agent (PCA) effected the morphologies and retarded the alloying extent of the milled powders. Finer, more uniform and spherical particles were obtained when steric acid (SA) was chosen as PCA. Increasing ball to powder ratio (BPR) would lead to efficient reduction of average particle size, but decrease powder yield and increase contamination.