Research Of Process Method About Dispersion And Strengthened Copper Composite With Mosi₂Content

Dispersion and strengthened copper is widely used in fields of automobile and electron industry. Metal silicide MoSi2can be used as consolidated phase of electric conduction copper owing to its excellent properties such as high strength and hardness, thermal expansion coefficient matching with copper, good electric and heat conductivity in itself and furthermore, it has small effect on electric conductivity. So far no report about MoSi2dispersion and strengthening copper-base composite has been seen and this paper focuses on elementary research about preparation and properties of above material.Firstly, MoSi2powder was dispersed and refined by wet milling method and then the composite powder of MoSi2/Cu were prepared by mechanical milling method. Then bulk MoSi2/Cu composite was prepared by hot pressed sintering technique. Secondly, the evolution of particle size, grain size and micro-strain of MoSi2powder with the increase of milling time were investigated by means of laser grain analytic instrument(LPSA), X-ray diffraction(XRD) and scanning electronic microscope (SEM). At the same time, the microstructure of MoSi2powder by wet milling was also discussed. Thirdly, structure and morphology characteristic and microstructure evolution were researched. Finally, mechanics and electricity properties、microstructure、density of MoSi2/Cu sinter specimens were also studied.The results showed that the phase transformation of MoSi2didn’t occur after wet milling for100h, whereas grain size which decreased from13.634μm to0.140μm. Distribution plot for particle size presented the double-hump character of coexistence of sub-micro zone and nanometer zone. Average crystal grain was14.2nm; the grain size and micro-strain exhibited inversion relationship of ε=13.539D-0.3248during milling.The composite powder presented the following evolvement process during milling:at first forming mechanical coat body and then crashing and refining. The composite powder had optimal property after60h milling with the crystal size of copper decreased from54.3nm to14.4nm and that of MoSi2decreased from69.4nm to24.1nm, respectively. but further milling took little change.The energy decrease of system is the main drive force for sinter process. The properties of materials were dependent on density、sinter status and microstructure; materials with high density、thorough sinter and homogeneous structure had good property. The second phase、pore and solid solution impurities could decrease electric conductivity. Dispersion and strengthened copper composite with2%MoSi2content may be produced under the optimal process conditions that were proposed: relative density was97.44%, electric conductivity was68.42%IACS, hardness was HV142, tensile strength was356.21MPa.This work to broaden the dispersion strengthened copper alloy research areas. However, The preparation process and enhance phase interface wettability needs further research.