Tailoring the microstructure and tribological properties in commercially pure aluminium processed by High Pressure Torsion Extrusion

High Pressure Torsion Extrusion (HPTE) as a novel approach in mechanical nanostructuring of metallic materials and alloys has the potential to be utilized in industrial applications due to its unique features in fabricating bulk-nanostructured materials with enhanced mechanical and functional properties. Three different HPTE regimes based on the extrusion speed of the punch (v, mm/min) and rotational speed of the die (ω, rpm) were used in this work: v7w1, v1w1, and v1w3. The grain refinement obtained by this technique was outstanding since the initial grain size of 120 μm in annealed conditions was reduced to the final grain size of 0.7 μm in v1w3 in merely one pass of extrusion; however, each regime showed a different level of grain refinement depending on the imposed strain. Examination of the tribological properties by reciprocal wear testing in dry conditions revealed no significant change in the coefficient of friction; nevertheless, the mechanism of the wear from adhesion shifted to abrasion and the amount of displaced volume decreased. This modification is associated with the improvement of hardness and the reduction of plasticity in materials that confined the plastic shearing. Increasing the induced strain by changing the HPTE regimes decreased the overall displaced volume and reduced the built-up edge around the wear track

Analysis of the reciprocal wear testing of Aluminum AA1050 processed by a novel mechanical nanostructuring technique

This research aims to investigate the impact of a novel technique in mechanical nanostructuring on the wear resistance of materials. This technique with the name of High Pressure Torsion Extrusion (HPTE) can produce bulk nanostructured materials with enhanced mechanical properties. Results of microstructural analysis and microhardness testing showed significant enhancement in materials after HPTE. Microstructural characterization by using Electron Back-Scattered Diffraction (EBSD) method illustrated the presence of Ultra-Fine Grained (UFG) materials in the specimens Analysis of the wear by implementing reciprocal wear testing revealed that the amount of displaced volume markedly decreased after processing. This change in the wear behavior can be explained by referring to the hardness increase and the reduction of plasticity in materials which confined the plastic shearing and diminished the built-up edge around the wear track

Effect of Hard Cyclic Viscoplastic Deformation on Phases Chemical Composition and Micromechanical Properties Evolution in Single Crystal Ni-Based Superalloy

The phases chemical composition and micromechanical properties in single crystal of Ni-based superalloy with chemical composition of 12.1 Al, 5.3 Cr, 9.4 Co, 0.8 Nb, 0.9 Ta, 0.7 Mo, 2.5 W, 0.7 Re and Ni-balance (in at.%) were changed during hard cyclic viscoplastic deformation at room temperature. The method we used based on the Bauschinger effect. The changes in the dendritic microstructure and chemical composition were characterized by scanning electron microscopy and energy dispersive spectrometry. The phases micromechanical properties evolution were characterized by nanoindentation. The results show that the cumulative strain or strain energy density increase arouse the interdiffusion of atoms between the different phases and the phases equilibrium in SC was changed. It is established that the interdiffusion rate depends on elements atoms activation energy. The new γ-γ'-eutectic pools were formed in the primary dendrites region (with fine γ/γ'-phase) and as result the length of newly formed dendrites was decreased significantly. The maximal and plastic depth of nanoindentation were measured and the corresponding micromechanical properties of phases calculated

Microstructure, texture and mechanical properties of cyclic expansion-extrusion deformed pure copper

A recently developed severe plastic deformation technique, cyclic expansion-extrusion (CEE), was applied on a commercial pure copper to investigate the relationship between microstructure, texture and mechanical properties over a wide range of strains. Microstructure and crystallographic texture investigations were performed by optical microscopy, electron back scattering and X-ray diffraction. Significant evolution in grain refinement was achieved down to sub-micron grain size. A considerable texture evolution was also observed within the deformation zone with the extrusion as the decisive step for the final texture. Fiber deformation textures were observed; the 〈111〉 component was found to be the main texture component while the 〈100〉 component became significant only at very large strains. The evolution in hardness and tensile properties was studied and a clear relationship between texture evolution, microstructural parameters and mechanical properties was found and discussed

Tailoring the microstructure and tribological properties in commercially pure aluminium processed by High Pressure Torsion Extrusion

High Pressure Torsion Extrusion (HPTE) as a novel approach in mechanical nanostructuring of metallic materials and alloys has the potential to be utilized in industrial applications due to its unique features in fabricating bulk-nanostructured materials with enhanced mechanical and functional properties. Three different HPTE regimes based on the extrusion speed of the punch (v, mm/min) and rotational speed of the die (�, rpm) were used in this work: v7w1, v1w1, and v1w3. The grain refinement obtained by this technique was outstanding since the initial grain size of 120 μm in annealed conditions was reduced to the final grain size of 0.7 μm in v1w3 in merely one pass of extrusion; however, each regime showed a different level of grain refinement depending on the imposed strain. Examination of the tribological properties by reciprocal wear testing in dry conditions revealed no significant change in the coefficient of friction; nevertheless, the mechanism of the wear from adhesion shifted to abrasion and the amount of displaced volume decreased. This modification is associated with the improvement of hardness and the reduction of plasticity in materials that confined the plastic shearing. Increasing the induced strain by changing the HPTE regimes decreased the overall displaced volume and reduced the built-up edge around the wear track