Influence Of Stacking Fault Energy On The Strength And Ductility Of Cu And Cu Alloys

Cu and Cu alloys make a great contribution for human society, and were widely applied to our life. With the development of technology, we need a better and better on the mechanical properties for Cu and Cu alloys. We make different methods to improve material performance. For example, severe plastic deformation(SPD), high energy ball milling. By adding alloy elements can reduce stacking fault energy, thereby improve the mechanical properties of material.The paper focus their on different Cu-Ge, Cu-Al-Zn, Cu-Mn samples. These samples are taken metallographic microscope, micro-hardness test, X-ray Diffraction (XRD) test and tensile test. We can evaluation of the mechanical properties of the samples by analyzing for experimental results. With stack fault energy, we can discuss the average grain size, micro-hardness and plastic deformation mechanism of samples was observed.The relationship of material and stacking fault energy is Cu=78 mJ/m2, Cu-0.1 wt.% Ge=54 mJ/m2; Cu-5.7 wt.% Ge=15 mJ/m2. By observing the experiment results of XRD, we find that with the increasing Ge content of alloy, the stack fault energy decreased, leading to the grain size decreased, the micro-strain increased. By tensile test, the stack fault energy decreased, strength and ductility increased. Through the metallographic microscope, the grain refining can be observed, and the grains elongate along the deformation direction.Cu-Al-Zn powder was prepared by high-energy ball milling. Powders micro-structure were studied at different conditions using X-ray diffraction. The effect of milling time and stacking fault energy on the mechanical properties of Cu-Al-Zn alloy were studied. Different composition and preparation process on the mechanical properties of Cu-Al-Zn alloy was studied in the same stacking fault energy. The results show that with increasing of the milling time and decreasing of stacking fault energy the grain size is becoming smaller and smaller, at the same time lattice distortion rate is becoming larger and larger. With the increasing of milling time and decreasing of stacking fault energy the micro-hardness of samples was increased. And the relation between grain size and micro-hardness meet the Hall-Petch relation well. Cu, Cu-2.87 wt.% Mn, Cu-4.40 wt.% Mn and Cu-10.19 wt.% Mn were prepared by cold-forging. The deformation behavior of Cu-Mn alloys is consistent with the Cu-Ge alloys, which not lower the stacking fault energy to simultaneously increase the strength and ductility. With increase Mn, the grain size decreased, the dislocation increased, but there is nearly no change for twin density.