Deformation mechanisms to ameliorate the mechanical properties of novel TRIP/TWIP Co-Cr-Mo-(Cu) ultrafine eutectic alloys

Effects of the Prefabricated Cu-Ti Film on the Microstructure and Mechanical Properties of the Multiphase Coating by Thermo Plasma Nitriding on C17200 Cu Alloy

To improve the surface wear resistance, plasma nitriding of the prefabricated Cu-Ti films on the C17200 Cu alloy is performed to investigate the effects of the composition of the Cu-Ti films on the microstructure and the mechanical properties of the modified surface. The results firstly showed that obvious microstructure evolution appeared during the thermo-plasma nitriding process, where both the surface morphology of the composed phases and the cross-sectional profiles of the multiphase coatings varied for the three types of films. Small amounts of Ti-N compounds, Be3Ti2Cu, and different types of Cu-Ti intermetallics formed in the multiphase coating after plasma nitriding, which is dependent on the composition of the prefabricated Cu-Ti film. Correspondingly, the surface hardness and the wear resistance of the C17200 Cu substrates were obviously improved, with the obtained adhesive strength of the substrate reaching a satisfactory range.

Effect of Functionalized Graphene Nanoplatelets on the Delamination-Buckling and Delamination Propagation Resistance of 3D Fiber-Metal Laminates Under Different Loading Rates

This paper presents an investigation into the effect of graphene nanoplatelets (GNPs) as a means of improving the impact buckling performance and delamination propagation resistance of a recently developed 3D fiber-metal laminate (3D-FML). One of the highlights of the investigation is the examination of the performance of the GNP-reinforced resin at a sub-freezing temperature (−50 °C). 3D-FML beam specimens were subjected to axial impact of various intensities at room-temperature, while they were subjected to quasi-static axial compression load at the sub-freezing temperature. Moreover, the influence of two different surface preparation methods on the performance of the metallic/FRP interfaces of the hybrid system was also investigated in this study. Although the inclusion of the GNPs in the resin resulted in some gain in the buckling capacity of the 3D-FML, nevertheless, the results revealed that the lack of adequate chemical bond between the GNP-reinforced resin and the magnesium skins of the hybrid material system significantly limited the potential influence of the GNPs. Therefore, a cost-effective and practical alternative is presented that results in a significant improvement in the interfacial capacity.

Thermally-triggered Dual In-situ Self-healing Metallic Materials

The microstructural evolution and crack filling phenomena of (Al₈₁Cu₁₃Si₆)_100−x(Sn₅₇Bi₄₃)_x (x = 0, 1, and 3 at.%) composites was investigated. The Sn and Bi elements were selected by considering the ability for liquid phase separation when combined with Al, Cu, and Si. Because of liquid phase separation, both Al-Cu-Si-rich L₁ and Sn-Bi-rich L₂ phases separately solidified at different temperatures yielding a trimodal eutectic structure in the cast alloys. The Sn and Bi elements have high mobilities due to the large interface of the eutectic microstructure and tend to strongly diffuse towards higher strained region during heat treatment. Furthermore, the mobile Sn and Bi elements in the Al-Cu-Si-based bimodal eutectic structure evidently fill cracks during warm rolling at 423 K. These results reveal that the developed alloy system has simultaneously dual self-healing characteristics, derived from the both precipitated Sn-Bi-rich particles and low melting agent, and the proposed alloy design based on liquid phase separation provides a novel strategy for creating self-crack filling metallic materials.