Guanghai Feng

Finite element analysis of pressure on 2024 aluminum alloy created during restricting expansion-deformation heat-treatment

Abstract Metals heat-treated under high pressure can exhibit different properties. The heat-induced pressure on 2024 aluminum alloy during restricting expansion-deformation heat-treatment was calculated by using the ABAQUS finite element software, and the effects of the mould material properties, such as coefficient of thermal expansion (CTE), elastic modulus and yield strength, on the pressure were discussed. The simulated results show that the relatively uniform heat-induced pressure, approximately 503 MPa at 500°C, appears on 2024 alloy when 42CrMo steel is as the mould material. The heat-induced pressure increases with decreasing the CTE and the increases of elastic modulus and yield strength of the mould material. The influences of the CTE and elastic modulus on the heat-induced pressure are more notable.

First-principles study of stability and properties on β-SiC/TiC(111) interface

The interfacial properties of β-SiC/TiC(111), such as work of adhesion, interface energy, fracture toughness, bonding nature, were investigated using first-principles calculations. Twenty four interface models with different terminations, carbon sublattice, and stacking sites were investigated. The thermodynamic stability of SiC/TiC(111) decreases as the order of C/C, Si/Ti, C/Ti, and Si/C terminations. The C/C-terminated top-site-stacked models (CCU3, CCT3) are most stable with the largest work of adhesion, smallest interface energy, and largest interfacial fracture toughness. The interfacial fracture toughness is predicted as 3.6 ∼ 4.3 MPa·m1/2. The valence electron density and partial density of states indicate that the interfacial bonding is mainly contributed from covalent C-C interactions caused by the hybridization of C-2p. The interfacial Si-C and Ti-C bonds are less covalent and much weaker than the interior ones, and the interfacial bonds are more inclined to decompose. The carbon layer is likel...

A review on the research progress of push-out method in testing interfacial properties of SiC fiber-reinforced titanium matrix composites

Experimental analysis of single-fiber push-out for SiC fiber-reinforced titanium matrix composites (TMCs) is complicated by the incorporation of large thermal residual stresses, strong chemical bond of the fiber/matrix interface and matrix plastic deformation. This paper summarizes the development of push-out test and the characteristics of push-out test for TMCs such as crack initiating at the bottom face and theoretical analysis of the test. Moreover, it deeply analyzes the progresses of interfacial shear strength and fracture toughness, and work focus is pointed out in future.

Effect of Hot Isostatic Pressing Parameters on the Microstructures and Grain Growth Behavior of the Matrix of SiCf/Ti-6Al-4V Composites

Abstract The SiC f /Ti-6Al-4V composites were fabricated by the matrix-coated fiber (MCF) process under two different hot isostatic pressing (HIP) processing parameters. Both microstructural characteristics and grain growth behavior in the matrix were investigated based on a combination of experimental observations and theoretical predictions. The main microstructural characteristics including matrix component phases and their corresponding chemical composition, morphology and volume fraction were systematically examined using EDS and SEM analyses, providing valuable insight into understanding the matrix microstructural evolution during consolidation processing from initial Ti-6Al-4V matrix-coated fibers (MCFs) to the final SiC f /Ti-6Al-4V composites. A dynamic recrystallization (DRX) model coupled with Lifshitz-Slyosov-Wagner (LSW) theory were also used to predict the grain growth occurring in the matrix during consolidation processing. Correlation between the theoretical predictions and experimental results were also discussed.

Fatigue behaviors of C/Mo double-coated SiC fiber-reinforced Ti6Al4V composites with varied interfacial microstructure

Fatigue crack propagation behaviors of the as-prepared and thermally exposed (700 °C/196 h, 800 °C/196 h) C/Mo double-coated SiC fiber-reinforced Ti6Al4V composites were investigated. The results show that interfacial microstructure evolution has significant effect on fatigue crack propagation behaviors. As for the as-prepared and 700 °C/196-h thermally exposed composites, fiber-bridging accompanied with interfacial debonding can decrease the crack growth rate significantly, while the latter one has lower crack growth rate at the early fatigue crack propagation stage, as the diffusion of Mo atoms makes the matrix close to the interface have more ductile β-Ti. However, fiber-bridging phenomena disappeared with the altered interface in the composite after 800 °C/196-h thermal exposure. Fatigue fracture analysis further reveals that multistep deflections of crack in interface contribute to the improvement of interface toughness. The formation of ductile β-Ti layer resulted from the diffusion of Mo atoms is beneficial to blunt the crack tip.