Effects of Milling Technology on the Microstructure of Al_2O_3/Mo Composite Material

In view of coarse grains of in-situ synthesized Al2O3 particle enhanced molybdenum-based composite material,the composite grains are refined together with sol-gel method and high energy ball milling technique.The microstructure of Al2O3/Mo composite powder and composite material prepared by different milling processes were observed and analyzed by XRD and SEM.The results show that with milling time increasing,the appearance of the composite powder particles changes from ball shape to lamel shape and then to small ball shape,particle size changes from around 1.5 μm to 500 nm,and the molybdenum grains are refined gradually.Both dispersibility and refinement degree of the powder prepared at high ball/powder weight ratio are better.Improved milling speed results in reduced uniformity of powder particle size and powder agglomeration,hindering powder refinement.Nanoscale Al2O3 enhanced molybdenum-based composite material can be obtained by pressing and sintering and with the composite powder prepared under the conditions of ball/powder weight ratio 5∶1,rotation speed 300 r/min and milling time 60 h.