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We have investigated {332} twinning and detwinning mechanisms in β-Ti alloys. Microstructure-twinning relations were evaluated in a β-Ti-15Mo (wt.%) alloy by statistical analysis of the evolving twin structure upon deformation by in-situ SEM testing and electron backscattering diffraction (EBSD). We find that most of the primary twins (~80%) correspond to the higher stressed variant and follow Schmid’s law with respect to the macroscopic stress. Detwinning mechanism was evaluated in a multilayered β-Ti-10Mo-xFe (x: 1-3 wt.%) by EBSD. We find that the detwinning process consists of two independent events that occur at two different microstructural regions, i.e. twin tips located at grain interiors and grain boundaries. Both detwinning modes can be explained from a thermodynamic standpoint where the boundary dissociation processes minimize the boundary free energy.

Titanium and its alloys have been widely used as implants replacing hard human tissues in biomedical fields. To improve the stability of implants in the surrounding bone tissues, the materials with porous structures were fabricated. In this paper powder metallurgy technique was employed to fabricate porous Ti-39Zr-6Nb (wt.%) alloys. The porous structures and mechanical properties of the porous alloys were examined by scanning electron microscopy (SEM) and compressive tests. The results showed that with increasing the sintering temperature the porosity of the alloys decreased and the compressive strength and the elastic modulus increased. The porosity of the alloys was in the range from 20.8% to 23.2%, and the pore sizes mostly centered in 10~30μm. The compressive strength and the elastic modulus were in the range from 110.4 to 292.4MPa and 4.7 to 12.4GPa respectively, which was close to human bone.

One of the disadvantages of β-Ti alloys is rapidgrain coarsening at elevated temperatures due to accelerated diffusion in the βphase region. Microstructural stability of β-Ti alloys would depend on theirability to maintain refined grains or microstructures at high temperatures. Thebeta grain growth kinetics of a newly designed beta titanium alloy has beensystematically investigated in this research. The grain growth exponent (n) value is at the range of 0.1-0.2,about 0.1 at low temperatures and about 0.2 at high temperatures over 950°C. Itis lower than other beta titanium alloys. The reason of lower n values can be investigated in the viewof the solute and the diffusivity in the titanium matrix.

Ti-6Al-4V plates in thickness of 8 mm were directly hot rolled and then heat treated in various routes by a single electron beam cold hearth melted (EBCHM) ingot, in which the weight percentage of recycled titanium scraps was at least about 50 wt%. The dynamic stress-strain behaviors of the plates with typical microstructures were investigated by Split Hopkinson Pressure Bar system at the strain rates of 2000 s-1~ 3000 s-1. The results show that the dynamic compression properties of EBCHM-ingot Ti-6Al-4V plates are relative to that of commercial VAR-ingot plates. The dynamic properties in normal direction of the plates are not sensitive to variations in the fraction of primary alpha phase.

Currently, the traffic congestion is a significant problem encountered in urban development, which should be resolved depending primarily on the management and deployment under the circumstance that road construction isn't able to keep the pace of automobile growth. WSNs (Wireless sensor networks), made up of numerous sensor nodes, form a multi-hop and self-organizing cellular system by wireless communication, which can realize real-time monitoring and collecting environmental information by cooperation. In this paper, a design of real-time and dynamic city vehicle navigation system is presented based on WSNs, GPS(Global Positioning System), and GPRS(General Packet Radio Service) techniques..

Ti-Al-Mo-Fe alloys were developed as low cost beta Ti alloys for automotive springs, and designed based on Molybdenum equivalency and Bo-Md molecular orbital method. Low priced Mo-Fe master alloys were introduced as alloying elements for the cost and elastic modulus reduction. Eight Ti-Al-Mo-Fe alloy candidates were pre-designed according to the Bo-Md method. Primary laboratory scale ingots were thus melted by ISM (Induction Skull Melting). After primary property evaluation, the Ti-2Al-9.2Mo-2Fe alloy was optimized finally and large scale ingot was made by VAR for further property evaluation. Resultantly, it shows that the alloy has lower elastic modulus (60-70 GPa) and good tensile properties in the solution condition, and compares well with the other developed commercial beta alloys.

The reliability control of reinforced concrete structure during construction is important for ensuring the safety of the structure. The paper puts forth the main influence factors of construction quality and the control measures of these factors through the discussion of reliability control of construction quality, and given the processing method of quality defects of reinforced concrete structure during construction.

Microstructure characterization and hardening behavior of a new designed Ti-12.1Mo-1Fe alloy during solution and aging treatment was investigated in the present study by OM, Vickers hardness. The results showed that the beta transus temperature of new Ti-12.1Mo-1Fe alloy was about 780°C. Further observation of ω phase should be performed by TEM later. It is also found that ω phase played a more important role than α phase in hardening. The hardening due to ω phase can lead to a high hardness about 470 Hv but the coarse α phases result in a hardness below 300 Hv.

The microstructure evolution of a new designed metastable beta Ti-9.2Mo-2Fe alloy during aging treatment was investigated by TEM. The results revealed that athermal ω phases were observed in SAD pattern during water quenching from above the β transus temperature for the alloy. As well, isothermal ω phases were found during aging at 500 °C even though they have a limited time of stability. The coexistence of ω and α phase was found in the early aging time and the pre-formed ω phase during aging undergoes coarsening and act as uniformly distributed nucleation sites for α precipitation during subsequent isothermal aging treatment. A consequence of such ω- assisted nucleation is that relatively large amount of α precipitations are formed and fine distributed in β matrix. In addition, the α precipitations are of a relatively finer size scale (nanometers to sub micrometers).

Ageing behaviors and microstructural characterization by aging condition of Ti-Al-Mo-Fe alloy was investigated. Due to the formation of ω phase, it occurs a drastic change in mechanical properties of β alloys. There is large increasing in hardness and yield strength, accompanied with serious ductility reduction. However, it has been proved that proper control of ω phase volume fraction can bring to improve strength with a reasonable ductility. In this work new beta titanium alloy was designed and developed in Ti-Al-Mo-Fe alloy to investigate the hardening behavior of ω and α precipitation during aging. The results showed that a small amount of athermal ω was observed in the β matrix during water quenching from above the β transus temperature. Isothermal ω formation was also found during aged at temperatures ranging from 573 K to 773 K although it has a limited time of stability at 773 K. The hardening due to isothermal ω precipitation exhibits no over-aging effect as long as ω phase exists inside the matrix. The hardness of this alloy is very sensitive to size and volume fraction of ω phase and its existence, which depends on aging temperature, time and alloy compositions.