High Energy Ball Milling Preparation Of Nanocrystalline Cu Materials

The nanocrystalline copper material was prepared successfully through the high energy ball milling by using pure copper powder as the raw material. We have studied the relationship of ball milling time and samples' microhardness, grain size, the relationship of samples' microhardness and grain size, annealing temperature.The microhardness of milled for different times samples was tested.The microstructure of samples was observed through optical microscope. The average grain size of milled for 3 hours, 7 hours, 9 hours and 12 hours samples was computed through X beam diffraction analysis uniting the Sherrer formula. The superficial appearance of samples was observed with the scanning electron microscope. The results indicated that, the microhardness of samples increased along with the ball milling time, when the ball milling time reach 9 hours, the microhardness of the sample arrived at the maximum 1.59GPa, hereafter the microhardness did not change along with the ball milling time. The grain size reduced along with the ball milling time increasing, the average grain size of samples which were milled for 3 hours, 7 hours, 9 hours and 12 hours was 30.1nm, 29.1nm, 27.8nm, 27.7nm, respectively. The microhardness of nanocrystalline copper samples increased along with the grain size decreasing. Through annealing treatment on 100 ℃ ~ 400 ℃, the microhardness of milled for 7 hours, 9 hours, 12 hours samples maintained at 1.25GPa, which indicated the thermal stability of the nanocrystalline copper samples was fairly good. The scanning electron microscope observation indicated that, there was much porosity in the sample, which indicated the density was not high.