A Study On The Microstructure And Property OfComposite Prepared By A New Type Vacuum Internal OxidationTechnique

Cu-Al2O3 metal matrix composite is widely used as electronic packing material, or electrodes and contact terminals, because of the combination of high electrical and thermal conductivity as well as high strength.In this paper, metastable Cu-Al alloy powder with different aluminum content was prepared by mechanical alloying technique. High strength and high conductivity Cu-Al2C>3 composites were prepared by a new type vacuum internal oxidation technique. The condition which the internal oxidation reaction of Cu-Al alloy can take place has been studied; technique parameters have been set on the basis of theoretical analyze; different factors which can affect the microstructure and properties of Cu-Al2O3 composites have also been discussed. The ambient temperature properties and the thermal stability of composites were tested. Several electrical conductivity models were optimally selected to calculate the electrical conductivity of Cu-AhOa composites .The results showed that:1. After the Cu-Al mixed powder was milled 96h, the lattice constant of Cu (111) plane became 0.3653nm, and the diffraction peaks of aluminum have disappeared completely, which showed that aluminum atoms have dissolved in crystal lattice of copper.2. Under the present experimental conditions, the oxygen partial pressure which the internal oxidation reaction of Cu-Al alloy can take place should be between 8.64 X 10~28Pa to 10~2Pa, without strict request. Two types of internal oxidation techniques were adopted, namely internal oxidation under nitrogen protect and new type vacuum internal oxidation in the present study. Both techniques can achieve the oxygen partial pressure that the internal oxidation reaction of Cu-Al alloy can take place.3. During the course of new type vacuum internal oxidation reaction, homogeneous dispersed a -AljOs particles were formed in copper matrix.The average size of A12O3 particles and their distance are 120nm and 400nm respectively.4. Within the scope of experiment error permitted, the optimally selected model 1 anastomose the experiment values very well.Generally speaking, optimally selected model one can be used to calculate the electrical conductivity of Cu-A^Os composites.5. After high temperature annealing the hardness of the composites did not reduced obviously until 973K, this temperature greatly exceeds that of pure copper(after cold machining, the temperature is 423K). When the AliOa content is increasing, the hardness of composites are also increasing and the temperature at which the hardness obviously reducing are increasing too.6. The ambient temperature properties and thermal stability of Cu-AhOa composites approach the Glidcop series products fabricated by the SCM Company in USA, the electrical conductivity exceeds or approaches them, for example, the electrical conductivity and ambient temperature hardness of Cu-1.2Al2C>3Wt% compositesfabricated by SCM Company of USA are namely 46.4m/( ?mm2) and 143HB;accordingly the values attained in this paper are 47.3m/( -mm2) and 127HBrespectively.