Effect Of Aging On Microstructures And Properties Of Cu-Cr Alloy By Rapidly Solidification

The Cu-Cr alloy is a kind of high strength and high conductivity copper alloy, it is widely used in many areas. The segregation is eliminated and the grain size of crystal is became to smaller of the Cu-Cr alloy by rapidly solidification technology, and the purpose of improved the strength is achieved.In the foundation of a large number of literature and existing scientific research, this article has been selected a kind of Cu-2.5%Cr alloy what Cr atom content is 2.5% super-saturation alloy as the object of study. The samples of alloy are prepared in the spin casting in vacuum by some different parameters of cooling rate (the speed of copper roller is set at 15m/s ~ 25m/s). It can be acquired the 6 groups of different samples. Then, the approximate rate of cooling corresponding is calculated by the cooling condition of samples which the condition is determined by the Biot number. Through observant and analysis for the result that is the influence of cooling rate to grain size of crystal, subsequently it can be obtained the relationship with cooling rate and the strength and the conductivity of Cu-2.5%Cr alloy.Then, the different parameter of the aging treatment is separately selected to take the heat treatment on the alloy. It can be obtained the best aging parameter of Cu-2.5%Cr alloy is 500℃and 120min after comparing the microstructure and performance of treated samples. During the process of aging, it is found that the volume of the second precipitated phase is increasing along with the increasing of time, after observed its microstructure modality of the super-saturation Cu-2.5%Cr alloy by the optical microscope and the electronic microscope.Furthermore, the precipitated second phase is appeared in the vacancy, dislocation, grain boundaries and other place of crystal defect at first. The phase of Cr is usually diffused in the matrix with the spherical or the ellipsoid. And it is become coarsening obviously along with the process of aging. It can be got a conclusion is the Cr phase in identical ingredient alloy is reducing along with the increasing of solidification speed by analyze its XRD phase. Based on the experimental results, through the research for principle of strengthening and principle of conduction in the process of aging, the dynamic equations and relational expression of conductibility with aging time can be established according to the Avrami empirical equations during the Cu-2.5%Cr alloy inthe process of aging.