The Effect of Process Route on the Mechanical Properties and Microstructure Aluminum Al-Si-Cu-Mg-Mn Alloys

Equal-channel angular pressing (ECAP) is an effective fabrication process to modify ultrafine grain size. It is believed that the smaller grain size could improve the mechanical properties. In the present work, the solution treatment applied to Al-Si-Cu-Mg-Mn alloy. Furthermore, two models of ECAP have been done through one-to-three pass at room temperature. The microstructures were observed by optical microscope (OM) and scanning electron microscope (SEM). The micro-hardness of longitudinal plane was analyzed by vickers hardness test. The strength of ECAP materials at room temperature was obtained by using tensile test. The results show that the ECAP process has improved mechanical properties of alloys, which were the hardness and ultimate tensile strength tend to increase since single pass stage.

Medium-Frequency Electrical Resistance Sintering and Electrical Discharge Consolidation of Metallic Powders

Compacts of iron powders were prepared by medium-frequency electrical resistance sintering (MF-ERS) and electrical discharge consolidation (EDC). Structural and mechanical characterization was carried out in order to study the effect of the main processing parameters (current intensity and sintering time in MF-ERS and voltage and capacity in EDC). The compact properties resulted to be quite sensitive to the consolidation method and parameters. Porosities around 8% and microhardness of about 120 HV were reached. It is concluded that the MF-ERS process can be a best option for the consolidation of cemented carbide composites with composition WC-6wt.%Co. MF-ERS compacts of this composite show a very low porosity and reasonable uniform microstructure, preserving the original ultrafine grain size and an adequate hardness with a very quick processing cycle of the order of one second.

Production of Fine-Grained and Weak Texture Structure in an Mg-7Gd-5Y-1Nd-0.5Zr Alloy by Multi-Axial Forging

Multi-axial forging was employed to produce simultaneously ultrafine grain size and weak texture in an Mg-7Gd-5Y-1Nd-0.5Zr alloy. The results indicate that the structure of fine grain size and weak texture could be achieved after two cycles of multi-axial forging, which leads to a substantial mechanical properties improvement. The grain refinement mechanism and texture evolution of Mg-7Gd-5Y-1Nd-0.5Zr alloy during multi-axial forging have been investigated.