Study on Densification and Internal Oxidation of Cu-Al Alloy Powders during Sintering Process

Densification and internal oxidation during sintering process in preparation of Cu-Al₂O₃ composite with a new simpli-fied internal oxidation technique were investigated.The results show that as the sintering goes on,the density of the pressing mixed powder blank increases and is stabilized at 7.96g/cm³ after sintering at 950℃for 4 hours,which increases by 4.3% com-pared with unsintered blank at the same time,and internal oxidation of Cu-Al alloy particles ocnurs.A mass of fine Al₂O₃ parti-cles are dispersed in the copper base,the size of Al₂O₃ particles is about 10²0 nm in diameter,and the spatial distance between particles is about 25⁶0 nm.Theoretical analysis indicates that the blank will shrink and its density will increase when the di-ameter of pore is smaller than 27.5μm,on the contrary,it will expand and the density will decrease when the diameter of pore is bigger than 27.5μm.The variation of density is caused by the effects of shrinkage and expansion.