High-temperature titanium alloys are one of the most important research directions in the field of high-temperature aerospace alloys. They are mainly used in high-temperature-resistant components, such as blade disks, blades, and casings of aero-engines, and are key materials in a new generation of high thrust-to-weight ratio aero-engines. In the service environment of engineering applications, the creep resistance of high-temperature titanium alloys is one of the most important characteristic indicators. This paper reviews and analyzes the research status and progress on the creep properties of typical high-temperature titanium alloys in service in recent years. The effects of the creep parameters, alloy composition, and microstructure on the creep behavior of high-temperature titanium alloys are discussed, and various possible mechanisms for increasing the creep resistance of high-temperature titanium alloys are summarized.

Titanium alloys are widely used in aerospace, chemical, biomedical and other important fields due to outstanding properties. The mechanical behavior of Ti alloys depends on microstructural characteristics and type of alloying elements. The purpose of this study was to investigate the effects of different Cu contents (2.5 wt.%, 7 wt.% and 14 wt.%) on mechanical and frictional properties of titanium alloys. The properties of titanium alloy were characterized by tensile test, electron microscope, X-ray diffraction, differential scanning calorimetry, reciprocating friction and wear test. The results show that the intermediate phase that forms the eutectoid structure with α-Ti was identified as FCC Ti₂Cu, and no primary β phase was formed. With the increase of Cu content, the Ti₂Cu phase precipitation in the alloy increases. Ti₂Cu particles with needle structure increase the dislocation pinning effect on grain boundary and improve the strength and hardness of titanium alloy. Thus, Ti-14Cu shows the lowest elongation, the best friction and wear resistance, which is caused by the existence of Ti₂Cu phases. It has been proved that the mechanical and frictional properties of Ti-Cu alloys can be adjusted by changing the Cu content, so as to better meet its application in the medical field.

This paper reviews the dislocation slip behavior of α phase in α, near α and α + β titanium alloys dominated by α-Ti deformation under quasi-static loading. The relation of slip activity, slip transfer, slip blocking, twinning and crack initiation is discussed, mainly combined with in situ tensile technology. The slip behavior in Ti-alloys is analyzed in detail from the aspects of critical resolved shear stress (CRSS), grain orientation distribution and geometric compatibility factor m′. In addition, slip blocking is an important factor of the formation of twins and micro-cracks. The interaction of slip behavior and interfaces is clarified systematically. Finally, the insufficiency of current research, future research directions and key difficulties of study are also discussed.

The impact toughness of a high-strength metastable β titanium alloy (Ti-5Cr-4Al-4Zr-3Mo-2W-0.8Fe) with two typical microstructures is studied by Charpy impact tests. The bimodal microstructure (BM) and the lamellar microstructure (LM) are obtained by the solution and aging treatments and the β annealing, slow cooling and aging treatments, respectively. In the impact crack initiation process, the deformation capacities of the primary α (α_p) phase, secondary α (α_s) phase and transformed β (β_t) matrix in the BM are very different, and the stress gradient at the interface of the three causes the crack initiation. The lamellar α (α_l) phase and β_t in the LM satisfy the BOR relationship, and the effective slip transfer between α and β phases slows down the crack initiation. Meanwhile, the appearance of deformation twins in the LM improves the crack initiation energy. In the crack propagation process, the lack of coordinated deformation between the α and β phases in the BM leads to rapid crack propagation. In the LM, the deformation of α_l and β_t is relatively more coordinated, so the severe plastic deformation is only concentrated near the crack and at the interface. The secondary crack initiation and the crack propagation along the twin boundary reduce the stress concentration at the crack tip. The deformation twins and zigzag propagation path can improve the crack propagation energy. To summarize, the alloy with LM exhibits better impact toughness than the alloy with BM.