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In order to understand the microstructure evolution and the deformation mechanism of medium volume fraction SiCp/Al composite during hot deformation, the hot compression tests of 35 vol%SiCp/2024Al composite were investigated by Gleeble-1500D thermo-mechanical simulators over hot deformation temperatures range of 623–773 K and strain rate of 0.01–10 s−1. The microstructure in different deformation conditions were investigated utilizing OM, SEM and TEM. The results indicated that the flow stress, microstructure evolution, and the deformation mechanism are sensitive to deformation parameters, which can be represented by the Zener-Hollomon parameter (Z) in the hyperbolic sine equation. The softening mechanism, the degree of dynamic recrystallization, the average grain size, the size of precipitates, the dislocation density, and the nucleation mechanism of dynamic recrystallization of the experimental composite is associated with the Z parameter. The specific influence relationships are analyzed, and the interaction laws are obtained.

In this work, the nucleation and growth behavior of Ti2AlC and Ti3AlC nano-precipitates in Ti–44Al–1.2C alloys were systematically studied by observing their distribution, morphology, and interface atomic structure. The experiment results show that the needle-like C atom segregation zones in TiAl alloys are the nucleation site of Ti2AlC, and the long axis direction of segregation zones is parallel to the TiAl(111) plane. The rod-like Ti2AlC nano-precipitates mainly distribute at the TiAl/Ti3Al interface, and the orientation relationship between them is [1̅01\bar{1}01]TiAl//[112̅011\bar{2}0]Ti2AlC//[112̅011\bar{2}0]Ti3Al, (111)TiAl//(0001)Ti2AlC//(0001)Ti3Al. The needle-like Ti3AlC nano-precipitates distribute in TiAl with the orientation relationship of [001]Ti3AlC//[001]TiAl, (100)Ti3AlC//(100)TiAl, (020)Ti3AlC//(020)TiAl, and (110)Ti3AlC//(110)TiAl during the nucleation stage. After growing into the rod-like, the orientation relationship between Ti3AlC precipitates and TiAl is [11̅01\bar{1}0]Ti3AlC//[11̅01\bar{1}0]TiAl, (001)Ti3AlC//(001)TiAl, (220)Ti3AlC//(220)TiAl, and (111)Ti3AlC//(111)TiAl. Both the needle- and rod-like Ti3AlC precipitates preferentially grow along the [001]TiAl direction. The crystal structure and lattice mismatch between Ti2AlC and Ti3AlC nano-precipitates and the TiAl matrix determine their distribution, morphology, and interface atomic structure.

Thermal deformation can improve the properties of aluminum matrix composites (AMCs) prepared by powder metallurgy (P/M) due to the dense and uniform microstructures. And the final microstructure of the AMCs is related to the dynamic recrystallization (DRX) behavior and nucleation mechanism in the thermal forming process. In this regard, the hot compression tests of dual-scale SiC particles reinforced A356 (SiCp/A356) composites prepared by P/M method were carried out at temperatures of 460–520°C and strain rates of 0.01–5 s−1 on a thermal simulation tester. The corresponding microstructure evolution was analyzed by electron back-scattered diffraction and transmission electron microscopy. The results indicated that the stress–strain curve was a typical DRX unimodal stress curve. The comprehensive influences of the strain rate and deformation temperature on the stress were investigated using the Zener–Hollomon parameter (Z), where the deformation activation energy was 443.204 kJ/mol. The DRX critical strain model and DRX volume fraction model were established. DRX behavior of the SiCp/A356 composites was sensitive to the deformation temperatures and strain rates. The micro and nano SiCp can promote the DRX nucleation of Al matrix due to the particle-stimulated nucleation.

This research focuses on the addition of low-cost rare earth metals (REMs) to improve the comprehensive properties of hyper duplex stainless steels (DSSs). The effects of REM on the microstructure, mechanical properties, and pitting corrosion of hyper DSSs were analyzed by optical/scanning electron microscope metallographic examination, X-ray diffraction analysis, tensile test, impact test, and potentiodynamic polarization test. With the addition of REM, micro/nanoscale REM inclusions were formed, and the microstructure of the alloy was refined. With the increasing content of REM, the average diameter and area of inclusions in the alloy decreased at first and then increased. While the mechanical properties showed a trend of first increasing and then decreasing. An appropriate amount of stable REM inclusions could reduce the susceptibility of pitting corrosion and improve the pitting corrosion resistance of the alloy. The hyper DSSs with REM content in the range of 0.018–0.031 wt% have excellent mechanical properties and pitting resistance.

The micromechanical behavior of an Al/Al2Cu/Cu multilayer with characteristic crystal orientation during uniaxial tensile deformation was investigated by molecular dynamics. The simulation results showed that under tensile loading, the dislocation nucleates at the Cu/Al2Cu heterogeneous interface and moves toward the Cu layer along the {111} crystal plane. The deformation mechanism is intralayer confinement slip. As the dislocations proliferated, interactions between them occurred; resulting in the formation of insertion stacking faults and deformation twins in the Cu and Al layers. However, no dislocation lines were generated in the Al2Cu layer during tensile deformation. As the load increased, the stress concentration at the Al2Cu/Al interface led to the fracture of the complex. In addition, the microplastic deformation mechanism and mechanical properties of Al/Al2Cu/Cu composites at different temperatures and strain rates were significantly different. These results revealed the microdeformation mechanism of laminated composites containing brittle phases.