Effect of ball milling time on microstructures and mechanical properties of mechanically-alloyed iron-based materials

The microstructures and mechanical properties of an iron-based alloy (Fe-13Cr-3W-0.4Ti-0.25Y-0.30O) prepared by mechanical alloying were investigated with scanning electron microscope, optical microscope, X-ray diffractometer and hardness tester. The results show that the particle size does not decrease with milling time because serious welding occurs at 144 h. The density of the alloy sintered at 1 523 K is affected by the particle size of the powder. Finer particles lead to a high sintered density, while the bulk density by using particles milled for 144 h is as low as 70%. In the microstructures of the annealed alloy, large elongated particles and fine equiaxed grains can be detected. The elongated particle zone has a higher microhardness than the equiaxed grain area in the annealed alloys due to the larger residual strain and higher density of the precipitated phase.