Abstract: The purpose of this paper is to determine the influence of temperature of plastic deformation on the structure and mechanical properties of copper alloys of the types CuCo1NiBe (CCNB), CuCo2Be (CB4), CuNi2SiCr (CNCS), CuNi1P (CNP) and CuCr1Zr (CW106C) applied on electrodesduring a tensile test. Tensile tests were carried out on polycrystalline samples of above mentioned alloys, which confirmed the presence of inhomogeneous plastic deformation in specified temperature ranges for each alloy. The tensile test of the investigated copper alloys were realized in the temperature range of 20÷800 °C with strain rate of 1.2•10-3s–1 on the universal testing machine. Metallographic observations of the structure were carried out on a light microscope and the fractographic investigation of fracture on an electron scanning microscope. Performed experimental studies have proven that analyzed structural factors, in a range of investigated strain conditions at elevated temperature, significantly influence the phenomenon of the Portevin Le Chatelier (PLC) type instability of plastic strain, revealed in low-alloy copper alloys. Moreover, it was found that the impact of examined factors on the PLC effect should be considered comprehensively, taking into account their synergic interactions.
Abstract: Binary Mg-Ca and ternary Mg-Ca-Zn alloys are a new group of magnesium materials, which can be used in many goods. Among others, biomedical applications of these alloys mainly involved surgical implants in the form of plates or screws. In order to improve mechanical properties and corrosion resistance of Mg-based alloys with Ca and Zn addition in as-cast state a plastic deformation was applied by using the KOBO extrusion method. The microstructure studies conducted by scanning microscopy show that the structure of the alloys after the plastic deformation exhibits banding character and the bands are oriented in the direction of an extrusion. A significant increase of mechanical properties was observed for MgCa5Zn1 alloy. After the plastic deformation, the corrosion potential determined for the MgCa5 and MgCa5Zn1 alloy is shifted into the positive direction, which may suggest the increase of corrosion resistance. Moreover, the MgCa5 alloy in as-cast state was completely dissolved after 288 h of immersion in Ringer’s solution. A volume of hydrogen evolution for the same alloy after plastic deformation showed a value of 35 ml/cm2.
Abstract: The technology of structure refinement in materials with the aim of achieving substantial mechanical properties and maintaining the required plasticity level is becoming increasingly useful in industrial practice. Magnesium alloys are very progressive materials for utilization in practice thanks to their high strength-to-weight ratios (tensile strength/density). The presented paper analyses the effect of the input heat treatment of the AZ31 alloy on the change of structure and strength properties through the process of severe plastic deformation (SPD), which finds an increasing utilization, especially in the automotive and aviation industry. For the study of the influence of the SPD process (ECAP method) on the properties of the AZ31 alloy, two types of thermal treatment of the initial state of the structure were selected. The analysis of the structure of the AZ31 alloy was performed in the initial state without heat treatment and subsequently after heat treatment. In the next part, the influence of the number of passes on the strengthening curves was evaluated. Mechanical properties of the AZ31 alloy after ECAP were evaluated by hardness measurement and completed by structure analysis.