Effect Of Deformation On Mechanical Properties Of Copper And Copper Alloy

As we all know, copper products have excellent ductility, conductivity, and thermal conductivity, while the flaw of soft fatal. Therefore, how to increase its strength became our focus. And the Severe Plastic Deformation is our new breakthrough direction to improve its mechanical properties.In this paper, we research the pure-copper, copper-zinc alloy and copper-aluminum alloy with the surface mechanical attrition treatment technology, high pressure torsion technology and rolling technology of large plastic deformation method, respectively. We get the influence of different plastic deformation methods on the mechanical properties of the alloy. And make the representation of the micro mechanism of deformation with XRD.The surface grinding processing technology is used on the plastic processing machinery of the pure Cu, and its mechanical performance is tested by the tensile experiments. The metal material tensile strength develops with the increase of the mechanical milling time at both room temperature and liquid nitrogen temperature. We manage the pure Cu、Cu-10%Zn、Cu-20%Zn、 and Cu-30%Zn (stacking fault energy is γ=78mJ/m2、γ=35mJ/m2、γ=18mJ/m2and γ=14mJ/m, respectively) with the high pressure reverse plastic deformation methods. Due to lower fault dislocation will make all the obstacles when it’s difficult to pay slip or climbing, hinder the dislocation through the sliding and climbing back, dislocation reactions associated with fault can lead to dislocation density change, and strength and dislocation density are closely linked, so the higher of the zinc content in the sample, the lower of the fault energy then the higher of the tensile strength. The rolling at room temperature and rolling with liquid nitrogen temperature are used on the sample of Cu-2.2%Al、Cu-4.5%Al and Cu-6.9%Al (stacking fault energy is γ=35mJ/m2、γ=7mJ/m2and γ=5mJ/m2, respectively). We find that after rolling deformation processing, the grain sizes become smaller, and the strength develops. At the same time, low deformation temperature can promote the strength. Similar to the results of the sample managed with the high pressure torsion deformation, the lower of the stacking fault energy the higher of the strength. Then the samples are managed with annealing, whose strength increase firstly and then decrease expect the Cu-2.2%Al rolled at room temperature. So the annealing hardening appears. When the strength falls, the plasticity increases obviously. The annealing hardening becomes annealing softening. In the process of hardening, the sites of the maximum values of the annealing hardening are different because the alloy composition is different. The strength of the Cu-6.9%A1sample after rolling at liquid nitrogen temperature and annealing at200℃increase75.4MPa, which is the most typical embodiment of annealing hardening.In a conclusion, the performance of mechanics of materials can develop with not only Severe Plastic Deformation methods but also the change of the deformation temperature and the stacking fault energy. Only reasonable experiment design can achieve material mechanics performance indeed.