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Abstract: In the current paper, pre-compression is performed along the rolling direction (RD). Subsequently, the samples are deformed in plane-strain compression along the transverse direction (TD) and not allowed to expand in the normal direction (ND). The effect of plane-strain compression on the texture and anisotropy modification of a pre-twinned hot-rolled Mg–3Al–1Zn alloy is investigated by EBSD observation. The results reveal that the generation of double twins in the previous twins dominates the plane-strain pre-compression along TD while the twinning is difficult to occur in the matrix due to the constraint along ND. Additionally, the double twins generated in the previously formed twins effectively modify the compression behavior and enhance the compressive yield strength of the pre-compressed samples along ND. The anisotropy along RD, TD and ND is decreased. [Copyright &y& Elsevier]

Abstract: The effect of multidirectional pre-compression on the tension–compression asymmetry in a hot-rolled Mg–3Al–1Zn alloy is investigated in the present paper, revealing that the tension–compression asymmetry is greatly decreased via multidirectional pre-compression. The analysis of deformation behaviors through in situ EBSD observation demonstrates that the double twins could be generated in the previously formed twins and the existing double twins could be de-twinned to the twins under favorable orientations. De-twinning could happen through the movement of the boundaries and the nucleation of new lamellas. In addition, the twins are difficult to occur in narrow twins under low stresses, causing de-twinning to also happen in the double twins even though their orientation facilitates the activation of twinning. [Copyright &y& Elsevier]

To realize strength-ductility balance in a novel titanium alloy Ti–6Mo-3.5Cr–1Zr, the microstructure transition of stress-induced β→ω was intendedly retarded by design of α-β hybrid structure. The outstanding quasi-static tensile properties with yield strength of ∼825 MPa, true tensile strength of ∼1171 MPa and total elongation of ∼29.7% was obtained via microstructure optimization. [Display omitted] • α" phase transformation is suppressed for improving yield strength in the material. • The SIω transformation is intendedly retarded by design of α-β hybrid structure. • Excellent strength-ductility balance is achieved via microstructure optimization. [ABSTRACT FROM AUTHOR]

Taking advantage of high strength of a titanium alloy and high ductility of the other one is performed to manufacture titanium laminated composite that is promisingly applied in high strain rate environments, but the challenge of fabricating high bonding interface of the two titanium alloys still needs to be overcome. In this work, the TB9/TC4 titanium laminated composite was successfully prepared by hot rolling. A strong bonding interface was constructed between the layers of TB9 and TC4 titanium alloys, achieving a high shear strength of up to 770 MPa. The dynamic compression of the TB9/TC4 titanium laminated composite under Split Hopkinson Pressure Bar (SHPB) showed that the stress-strain curve of the composite presented a unique dual-peak feature, indicative of an excellent strain hardening capability. The TB9/TC4 interface, characterized by coherent and low interface formation energy, facilitated deformation accommodation between TC4 and TB9 layers. Concurrently, the TB9/TC4 interface hindered the ASBs and triggered dislocation strengthening due to stress concentration, leading to high dynamic strength of the laminated composite. [ABSTRACT FROM AUTHOR]

Abstract: The effects of compressive pre-deformation along extrusion direction (ED) on yield asymmetry between tension and compression in hot-extruded Mg–3Al–1Zn (AZ31) alloy was investigated in this paper. {10–12}-type twinning occurred when samples were subjected to compressive pre-deformation. The compressive yield strength of sample with compressive pre-deformation increased gradually with the increase in compressive prestrain. The tensile yield strength of the sample decreased rapidly with the increase in compressive prestrain from zero to ~1.7%, but it was nearly unaltered when compressive prestrain was higher than ~1.7%. Detwinning occurred in the twinned regions played roles in the subsequent tensile process so that the yield stress was lower than sample without prestrain. Yield asymmetry between tension and compression decreased gradually when compressive prestrain was lower than ~1.1%, but it began to increase after that. It suggests that yield asymmetry can be effectively controlled by appropriate pre-deformation. [Copyright &y& Elsevier]

To promote the application of laminated composites with high strength and plasticity in armor field, the feature of interface bonding and the influential mechanisms accounting for the interface quality need clarification. In this work, laminated composites of high-strength TB9 and good-toughness TC4 were successfully manufactured by high temperature rolling with different thickness reduction. Microstructural observations indicate that the plastic deformation and recrystallization at the edge position of the laminated composites are greater than that at the center position. By contrast, the center position of the composites has better bonding quality than the edge position. Besides, holes are detected at the interfaces when the reduction is low. With the reduction increased, the interface bonding is improved and the positional quality difference of the interfaces is reduced. The shear and tensile tests show higher bonding strength and tensile strength with larger rolling reduction. LS-DYNA finite element simulation is performed to study the formation mechanism of the holes and the influential mechanisms on the positional difference in interface bonding quality of the laminated composites. A parameter δ considering the relative strain of the TB9 and TC4 is introduced to quantitatively evaluate the deformation coordination. When the reduction was 70%, the δ is the smallest with the largest bonding strength up to 676 MPa at the center position. [ABSTRACT FROM AUTHOR]

A novel metastable β-type Ti–6Mo-3.5Cr–1Zr alloy is designed using d-electrons theory to introduce diverse phase transformations. Stress-induced ω (SIω) phase transformation dominates the initial deformation, while the SIω bands are transformed to α+β phase as the strain increases. The sequential mechanism associated with β→SIω→α+β is first reported in titanium alloys. • A novel metastable β alloy Ti–6Mo-3.5Cr–1Zr is designed using d-electrons theory. • The stress-induced β.→ω→(β+α) phase transformation is firstly reported • Localized growth and combination of the single athermal ω variant form the SIω. • Elemental redistribution occurs during the stress-induced ω.→(β+α) process • The covalent bond gradually dominates during the β.→ω→α transformation [ABSTRACT FROM AUTHOR]