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Al matrix composites (AMCs) have gained tremendous interest in the past decades due to their lightweight, superior mechanical and other physical properties. In this study, an ultrafine-grained Al2024/1 wt% TiC/1 wt% graphene nanoplatelets (GNPs) nanocomposite was fabricated through powder metallurgy. Synergetic effects of TiC and GNPs on the microstructural characteristics, mechanical properties and thermal conductivity were investigated in comparison with those of the matrix and TiC or GNPs singly reinforced Al2024 matrix nanocomposites. The Al2024/1 wt% TiC/1 wt% GNPs nanocomposite showed significantly improved mechanical properties with the compression yield strength of 370.2 MPa, ultimate compressive strength of 615.8 MPa and fracture strain of 8.6%, indicating a superior balance in the strength and ductility over TiC or GNPs singly reinforced Al matrix composite, since the distributions of both the TiC and GNPs in Al2024/1 wt% TiC/1 wt% GNPs nanocomposite were improved significantly. The significant mechanical property improvements are attributed to the synergistic reinforcing contributions from TiC and GNPs. The thermal conductivity of Al2024/1 wt% TiC/1 wt% GNPs nanocomposite stables at 55.0 W∙m-1∙K-1 without a further decrease compared with the composite singly reinforced with GNPs. • An ultrafine-grained Al2024–TiC-GNPs hybrid nanocomposite (AlTG) was fabricated. • Introducing TiC and GNPs benefits uniform dispersions of TiC and GNPs in AlTG. • The hybrid composite (AlTG) shows a superior balance in the strength and ductility. • Improved dispersions of TiC and GNPs explain better mechanical properties of AlTG. • Excellent thermal conductivity of AlTG is remained compared with other composites. [ABSTRACT FROM AUTHOR]

The interfacial morphologies play a crucial role in mechanical properties of laminated/bimetal composite. This study investigates the effects of heat treatments on the interfacial characteristics, mechanical properties and fracture behaviour of a 2205 duplex stainless steel/AH36 carbon steel bimetal composite with varying interface situations fabricated by the hot-rolling and subsequent heat treatments. The bimetal composite was annealed from 850 °C to 1150 °C in steps of 100 °C with soaking 1 h. Heterogeneities of grain size and element concentration exist in the microstructural evolution of bonding zone adjacent to interface after annealing treatments, which were observed by the optical microscope and scanning electron microscope (SEM) coupled with the energy dispersive X-ray spectroscopy (EDS). It was found that the diffusion transition zone of Cr and Fe alloy elements between component 2205 and AH36 steel layers present an increasing trend with the rise of annealing temperature. The results of conventional, shear and compact tensile test indicate that the tensile strength of 2205/AH36 bimetal composite gradually decreases but the fracture elongation increases with the rising annealing temperature, the thicker alloy element diffusion zone results in the stronger interfacial shear strength and better ductility of bimetal composite, but the thick and strong interface has less positive effect than the mechanical properties of bimetal composite itself on preventing the fatigue crack growth across the interface. [ABSTRACT FROM AUTHOR]

Different annealing treatments at 400-900 °C for 1 h were applied on copper/SS304L composite sheets, and the evolutions of microstructure and mechanical properties were investigated in this study. It is found that the diffusion distance of the elements at the interface is slightly increased with the increasing temperature. In addition, the grain coarsening in copper, the phase transformation from BCC to FCC in SS304L, and the decreased dislocation density after annealing soften the composite sheets, leading to decreased hardness and strength, as well as significantly improved ductility, especially when the temperature exceeds 500 °C. • Different heat treatments at 400–900 °C were applied on Cu/SS304L composite sheets. • Diffusion at the interfaces is promoted with the increase of annealing temperature. • Microstructure transforms from BCC to FCC in the SS304L sides after annealing. • Microhardness of the composites decreases as annealing temperature increases. • The strength decreases and the ductility increases as temperature exceeds 500 °C. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel designed austenitising bending process was realised on a thermomechanical simulator. • Integrated effects of SNL, martensite packet, PA grain, DRV and DRX were responsible for the strength gradient. • Parent grain reconstruction and martensite variants can be achieved a more effective technique. • The high consistency between simulation and experiments means valuable reference of the current study to simulate rail clip forming process. A systematic study was carried out on a novel designed austenitising bending process to explore the effects of quenching temperatures on the evolution of microstructure and mechanical properties of high-strength micro-alloyed steel. Results reveal that the qualified parts could be bent into a satisfactory shape without spring-back and cracks in bending temperatures of 850–1000 °C. The simulation was applied to predict the equivalent stress, stress neutral layer (SNL) and plate thickness. Strength presents a decreasing trend with the increase of bending temperature owing to integrated influences of high-temperature dynamic recovery (DRV) and dynamic recrystallisation (DRX). Beyond that, SNL nearby the geometrical centre line throughout the plate thickness and dislocation pile-ups on the tension/compression zones are responsible for the smaller hardness on middle regions while higher hardness on the surface areas. Through austenite reconstruction, a smaller martensite packet size would directly improve the strength of the plates bent at a lower temperature. The prior austenite size may be related to the appearance of martensite variants but not necessary. Furthermore, the high accuracy by comparing the experimental results with simulation would provide a high-value reference for the practical manufacturing process of railway spring clips. [ABSTRACT FROM AUTHOR]