Nano-Surface Composite Coating Reinforced by Ta2C, Al2O3 and MWCNTs Nanoparticles for Aluminum Base via FSP

In the present work, an advanced technique was applied to coat an Al 2024 alloy with a surface composite layer reinforced with various nanoparticles. The surface of Al 2024 aluminum alloy was modified with Ta2C, Al2O3 and multi wall carbon nanotubes MWCNTs nanoparticles by friction stir process (FSP). An improvement in the surface of the fabricated nanocomposite due to the refinement of the microstructure grains was achieved. In addition, a significant improvement in the hardness and wear behavior was observed. The reinforcement particles were incorporated into double and triple hybrid composite particles to determine the most effective combination for the controlled properties. The results showed that for the composite reinforced with a double hybrid of Al2O3 and MWCNTs, the microstructure grains of the fabricated nanocomposite surface were refined by 40 times. The hardness was significantly improved, i.e., it was increased by 48% by incorporating the triple reinforcement (Ta2C, Al2O3, and MWCNTs) into the surface of Al 2024 aluminum alloy. The results of wear properties were in agreement with the results of hardness; the maximum wear resistance was obtained for Al 2024-Ta2C + Al2O3 + MWCNTs, and the wear rate was reduced by 11 times.

Rare Earth Oxide CeO2 Decorated Graphene Nanoplatelets-Reinforced 2024 Aluminum Alloy Matrix Composites Fabricated by Pressure Sintering Process

In this study, graphene nanoplatelets (GNPs) decorated rare earth oxide CeO2 (CeO2@GNPs) were synthesized by alcohol thermal reaction method and used to reinforce GNPs/2024Al composites fabricated by a pressure sintering process. The results indicated that the decorating CeO2 particles could further promote the dispersion of the GNPs as well the binding of GNPs to the matrix. As a result, the as-prepared 0.5 wt.% CeO2@GNPs/2024Al composites exhibited yield strength and tensile strength increased by 21.1% and 24.7% compared to these of the matrix, respectively. It is better than the mechanical strength values of the composite enforced with the raw GNPs of the same quality. The optimization of GNPs dispersibility and interfacial bonding with Al matrix promotes its effective role in load-bearing strengthening.

A Comprehensive Study On Soundness, Microstructure and Uniformity of 2024 Aluminum Cups Hydro-Mechanically Drawn at Elevated Temperatures

In the present research work, the hydro-mechanical deep drawing (HMDD) process of 2024 aluminum alloy is performed experimentally and numerically for elevated temperatures. The main variables of the forming process include the fluid pressure, the pre-bulge pressure and the process temperature. The effects of these parameters on the thickness distribution and uniformity index of the final product have been investigated. Using the hardness test, the preferred crystallographic orientation, the energy dispersive spectroscopy and microstructure images obtained from an optical microscope and a scanning electron microscope, the relationship between the grain size, hardness and the effective plastic strain are studied and discussed. The findings imply that the HMDD process without the pre-bulge pressure reduces the uniformity of the final product and, on the other hand, excessive increase in this parameter causes tearing of the workpiece. The hardness distribution along the cup wall was in agreement with grain refinement and the Hall-Petch relationship, but it was not correspond to the expectations made via the texture analyses. The images gained from the energy dispersive spectroscopy for different areas of the 2024 Al sample demonstrated that the Al2Cu precipitations in the product wall were finer than the other areas and mainly dispersed at the grain boundaries. This type of precipitation distribution was the main origin for increasing the hardness of the cup wall in comparison with the cup corner and bottom. In other words, the precipitation hardening overwhelmed the influence of the preferred orientation of the grains in HMDD operation of Al 2024.