The true stress—strain curves of TC16 alloy with a wide range of strain rates were investigated under uniaxial quasi-static tension and uniaxial dynamic compression with the Instron 8032 test machine and the split Hopkinson bar respectively. The results indicate that the true stress increases with increasing strain rate, while decreases with increasing temperature. Under the 10⁵ s⁻¹ high strain rate and temperature higher than 673 K, the true stress would even be less than that under quasi-static condition. A new method incorporating TC16’s stress—strain curve developing item was proposed to determine the coefficients in J−C model easily and to avoid the estimation of the adiabatic temperature rising. The Johnson−Cook dynamic constitutive relationship for TC16 was obtained for the first time. Good agreement was obtained between the model prediction and the experimental stress—strain curves for TC16 under both quasi-static and dynamic loadings.

The effects of thermohydrogen treatment on the microstructures of TC21 and Ti40 alloys as-cast were researched. The results show that the β phase content increases after charged hydrogen. Compound Ti_xH_y appears if H content reaches a certain content, which perfectly gathers on the grain-boundaries and/or dislocations and then diffuses into the grains. The microstructure of TC21 alloy after thermohydrogen treatment becomes fine and the best H content is 0.4% (mass fraction). However, the influence of thermohydrogen treatment on Ti40 microstructure is not obvious.

Ti-Al thin sheet with dimension of 450 mm×450 mm×0.2 mm was prepared by electron beam physical vapor deposition(EB-PVD) technology. The surface and cross-section pattern of as-deposited sample were studied by SEM and AFM, and then the composition and phase were analysed by XRD and EPMA. Finally, the effect on deposit by re-evaporation of Al was explored by calculating the ratio of re-evaporating capacity with depositing capacity of Al on the substrate. The results indicate that the evaporation process with Nb addition into the molten pool makes it earlier to reach the steady-state. The existing equiaxed crystal and columnar crystal along the cross-sectional may be caused by the transformation latent heat released during the transition course of atoms from gaseous state to solid state. The effect on deposit by re-evaporation of Al can be neglected because the re-evaporating capacity of Al is far below that of the depositing capacity.

The influence of heat treatment on the microstructure and damage tolerance property of Ti-6Al-2Zr-1Mo-1V titanium alloy was investigated. The large-thickness Ti-6Al-2Zr-1Mo-1V titanium alloy plate was produced by β-processing, following with duplex anneal in (α+β) phase field and β anneal, respectively. The fatigue crack propagation rate(da/dN) test and the fracture toughness(K_ⅠC) test of Ti-6Al-2Zr-1Mo-1V were performed. The results show that the annealing in (α+b) phase field, with increasing anneal temperature, prior β grain size and α colony size of Ti-6Al-2Zr-1Mo-1V remained constant approximately, α lamella mean size increases gradually; K_ⅠC increases and da/dN decreases respectively; when annealing in b phase field, prior β grain size and α colony size increases sharply, da/dN decreases drastically. β anneal is better than anneal in (α+β) phase field as to improve the damage tolerance property of Ti-6Al-2Zr-1Mo-1V.

The influence of deformation parameters including deformation temperature, degree and speed on the microstructure and mechanical properties of TA15 titanium alloy was studied. The volume fraction, size and aspect ratio of primary α phase in deformed TA15 titanium alloy were quantitatively characterized. With increasing deformation temperature, the volume fraction and size of primary α phase decrease. The aspect ratio of primary α phase decreases with increasing deformation temperature. The tensile strength of TA15 alloy deformed at 0.1 mm/s is higher than that at 0.3 mm/s. After thermoforming at 960 ℃, 0.1 mm/s, the tensile strength is the highest up to 1 035 MPa and the elongation is 13.5%. When the thermoforming temperature is 1 050 ℃, the strength and elongation are both relative low, because the microstructure is Widmanstaten structure.

Ribbons of the two-phase titanium alloy were fabricated by single-roller rapid solidification technique, and aged at high temperature. The microstructure of ribbon samples were characterized with X-ray diffractometer (XRD) and environmental scanning electron microscope (ESEM). The microstructures of the alloy are composed of α phase and supersaturated β phase, and X-ray diffraction results show that all peaks of the α and β phases shift slightly to smaller angles, which can be explained by the disordering growth pattern caused by the rapid solidification process. After aging at 960 ℃ in vacuum, the ribbon is composed of homogeneous α phase and β phase.

The effects of heat treatment on the microstructure and phase constitution of Ti-3Zr-2Sn-3Mo-15Nb (TLM) alloy were investigated by optical microscopy, X-ray diffractometry and transmission electron microscopy. The wear resistance of TLM alloy was tested by sliding wear in comparison with as-annealed Ti-6Al-4V and as-aged Ti-13Nb-13Zr. The results show that the specimen cooled from α+β dual phase region is mainly composed of β, α and α″ phases, while the specimen cooled from β single phase region is mainly composed of β and α phases, in which β phase is predominate. The coefficient of friction of TLM alloy treated at 680 ℃, 1 h, AC+510 ℃, 6 h, AC is smaller than that of others, thereby TLM alloy has a better wear resistance which is also proved by the surface topography after wear test.

Samples of Ti26 (Ti-V-Sn-Cr-Al-Zr-Nb) alloy were compressed on the Gleeble−1500 heat stimulation machine. The compression test was carried out at 900−1 150 ℃ and strain rates from 0.001 s⁻¹ to 10 s⁻¹. Flow stress data at various temperatures and strain rate were obtained; and the compressive true stress vs. true strain curves were measured and studied. The deformation activation energy was calculated. The results show that the flow stress of Ti26 alloy decreases with the increase of temperature and the decrease of strain rate, and the deformation activation energy is 278.11 kJ/mol in b phase region. The flow stress curves and deformation activation energy reveal that the main softening mechanism is dynamic recovery in b phase region. Constitutive equations were formulated to describe the temperature dependence of the flow stress over a wide range of strain rates.

Hot compressive deformation test of Ti-Al-Cu-Si alloy was performed on Gleeble-3500 hot-Simulator over the range of deformation temperature from 1 000 to 1 300 ℃, strain rate from 0.005 s⁻¹ to 5 s⁻¹, deformation degree from 40% to 70%, and samples of d 8 mm×15 mm were used. Change rules of microstructure were mainly studied. The results show that deformation temperature directly influences the nucleation growth and globurizing of grain, and with the temperature rising, the diameter of grain increases, the grain boundary widens. The effect of deformation degree on microstructure varies with deformation temperature. Equivalent diameter of grains shows a trend of falling before elevation with strain rate increasing and temperature rising.

The influence of interstitial content on mechanical properties of a new type of near α titanium alloy (Ti-Zr-Mo-Nb-Sn) at cryogenic temperature was studied. The results show that interstitial content affects the mechanical properties of the alloy at cryogenic temperature. Interstitial element atoms solving into lattice causes the increasing of degree of distortion, which limits the sliding and twinning of dislocations. Reducing interstitial content is beneficial to generation of dislocation sliding and deformation twins. With interstitial element content reducing, the impact toughness and the elongation of the alloy decrease rapidly while the strength decreases weakly. To obtain good over-all properties at cryogenic temperature, the interstitial element content in this alloy must be controlled to extra low grade.

To resolve the problem of low current efficiency and low reaction rate when preparing metal by electro-deoxidization method, various contents of CaO and CaCO₃ were added into the TiO₂ powder, which were compacted into pellets and sintered, and then conducted as the cathode. The morphology and contents of the cathode and products were studied by scanning electron microscopy and X-ray diffractometry, the effect of the additives were studied. The results show that formation of calcium titanate and change of microstructure within the cathode enhance the velocity of the direct electrochemical reduction of solid TiO₂ to Ti.

Ti-600 is one of the high performance titanium alloys used at 600 ℃, which was developed in Northwest Institute for Nonferrous Metal Research (NIN) in China. The tensile and creep properties of Ti-600 alloy with different thermal treatment conditions were investigated. The results indicate that Ti-600 alloy possesses favorite comprehensive properties solution-treated at  1 020 ℃ for 1 h, then air-cool, and aged at 650 ℃ for 8 h, finally air-cooling, especially possesses quite good creep resistance. The residual deformation is less than 0.1% for the alloy exposed at 600 ℃ for 100 h with the stress of 150 MPa, and the bimodal microstructures of the alloy are almost the same as that of the alloy treated by duplex thermal treatment, only needle primary a phases became relatively thicker and coarsened. The ultimate strength and the elongation of the alloy tested at ambient temperature are 1 080 MPa and 12%, respectively; while at 600 ℃, they are 690 MPa and 16%, respectively. The ductility of the alloy tested at room, temperature is no less than 5% after thermal exposing at 600 ℃ for 100 h.

Five new heat treatment processes were designed, which were divided into three groups by their characteristics. The microstructures and mechanical properties of the alloy after the five heat treatments and thermal exposure at 500, 550 ℃ for 100 h were tested. The results indicate that a little differences exist in the performance of mechanical properties at room-temperature after the five heat treatments, and the thermal stability is the key factor for determining heat treatment process. Among the three groups of heat treatment processes, the best thermal stability is achieved after the first group of heat treatment. After annealing treatment at intermediate temperature, some defects and uneven grain boundaries are remained, which leads to the reduction fractions of precipitations on unit grain boundary and the harmful effect of precipitations on grain boundary is weakened. The process of annealing at 650 ℃ for 4 h is recommended the best heat treatment process for Ti40 alloy.

The effect of heat treatment and rolling process on the properties and microstructures of Ti-26 (Ti-15V-3Al-3Cr-3Sn-Forming) sheet was studied. The results show that the best rolling temperature for Ti-26 alloy is in the temperature range from 900 ℃ to 950℃. Under this condition, the resistance of deformation and yield ratio are low and the alloy has better hot work ability. The alloy will achieve better mechanical properties and completely recrystallized b microstructure when the deformation ratio is not less than 60% and the solution temperature is 30 ℃ above the phase transformation temperature. The best heat treatment conditions are recommended as: 790℃, 30 min, AC or WQ followed by 510 ℃, 10 h, AC. Under this heat treatment condition the strength of the Ti-26 alloy is 1 230 MPa and the elongation is 15%.

Samples of Ti-Al-Zr-Sn-Mo-Si-Y alloy were compressed on the Gleeble-1500 heat stimulation machine. The compression test was carried out in the temperature range from 800 ℃ to 1 100 ℃ and strain rate range from 0.001 s⁻¹ to 10 s⁻¹. Stress-strain behavior and variation of microstructure of the alloy during hot compression were investigated. The experimental results show that the alloy is sensitive to temperature and strain rate, and the flow softening behavior is more obvious with the decrease of deformation temperature. At higher strain rate, discontinuous yielding is observed in β phase region. When deformed in α+β phase region, with the increment of deformation temperature, the lamellar α structures globularization is more quick and more uniform. When deformed in β phase region, coarse β grains can be got because of high deformation temperature.

The hot deformation characteristics of TiC particles reinforced titanium matrix composite were studied in the temperature range from 900 ℃ to 1 150 ℃ and in the strain rate range of 10⁻³−10 s⁻¹ by compression tests with Gleeble1500 simulator system. The flow behavior was described by the hyperbolic sine constitutive equation, and an average activation energy of 436.72 kJ/mol was calculated. The processing maps were calculated and analyzed according to the dynamic materials model. The maps show domains in some combinations of temperatures and strain rates and these domains are correlated with specific microstructural processes occurring during hot deformation by metallographic investigations and kinetic analysis. At the low strain rate domain occurs in the temperature range of 900−960 ℃ and strain rate range of 0.001−0.03 s⁻¹ superplasticity and dynamic recrystallization were observed. At a high strain rate domain occurs in the temperature range of 980−1 120 ℃ and strain rate range of 0.1−10 s⁻¹ the β phase undergoes dynamic recrystallization. Also, at a strain rate range of 0.1−10 s⁻¹ and the temperature range of 900−930 ℃, the material exhibits flow localization.

TiC reinforced Ti-6Al-4V matrix composites were fabricated by consumable arc-melting technology utilizing the reaction between titanium and graphite. The phase composition, microstructure and hardness of the TiC/Ti-6Al-4V composites were investigated by XRD, SEM and hardness testing equipment, respectively. The results show that the reinforcements are distributed uniformly in the matrix alloy. With the carbon content of the composites increasing from 0.15% to2.0%, the morphology of TiC transforms from particle into short-bar shape or chain-type consisting of featheriness or wheat-shape and finally into dendritic. Simultaneously, the hardness of the composites increases. The formation mechanisms of TiC can be analyzed as follows: the growth of dendritic primary TiC before the peritectic reaction is dominated by the solute concentration gradient, after peritectic reaction, the nucleation and growth of TiC in β-Ti leads to its forming of short-bar shape. The dendritic TiC mainly is distributed in the matrix grain, but the short-bar shape TiC mainly segregates at the grain boundary, especially at the triangular grain boundaries.

Ag-Sn-Cu-Bi-Ni alloy was internally oxidized in air. The phase constitution, surface morphology and microstructure evolution of the alloy after internal oxidation were analyzed by X-ray diffractometry, optical microscopy and scanning electron microscopy, respectively. The results show that the surface color of samples after internal oxidation is different from the different oxidation time and temperatures. The oxidation reaction firstly takes place on the grain boundaries. The microstructure developed on the initial stage of internal oxidation is fir-tree crystal texture. However, this texture structure disappears accompanied by grain growth and oxides forming during the prolonged oxidation. Finally, the oxide particles are uniformly dispersed in the silver matrix.

Tantalum nitride powders with particle size of 20−50 nm were prepared by the homogeneous reduction in liquid ammonia, and were treated at the temperature range from 500 ℃ to 1 170 ℃. The results of XRD analysis indicate that the powders heated up to 500 ℃ are in the form of amorphous. The powder heated at 600 ℃ tends to transform into crystal, the powder heated to temperatures higher than 700 ℃ is clearly of crystal. The results of surface area analysis by BET show that the surface area of the powder increases as the heating temperature increases, and reaches a maximum value of 21.8 m²/g at the heating temperature around 700 ℃.

For the doping technique with single dopant of Sb₂O₃, Ga₂O₃, In₂O₃, AlCl₃, Bi₂O₃ or Sm₂O₃, the dopant concentrations of 10%(molar fraction) were selected for the CeO₂-based oxygen-ion conductors. A wet chemical method by polymerization of polyvinyl-alcohol was performed for the compound preparation. X-ray diffraction analysis result shows that the calcined powders have nanocrystalline structure with grain size less than 40 nm, and the sintered samples have pure single fluorite-type phase in all doped cerium oxides. Impedance measurement results show that the conductivities and activation energies of CeO₂-based oxides depend closely on the dopants. The Sb₂O₃-doped CeO₂ has the largest conductivity and In₂O₃-doped CeO₂ has the lowest one at 200 ℃, the Bi₂O₃-doped oxide shows the highest activation energy and Al₂O₃-doped oxide shows the lowest one. Ionic radii and association enthalpies of dopants were taken account for different conductivities and activation energies of the CeO₂-based oxygen-ion conductors.

The wear behavior of Ni-Cr-based alloys was investigated at ambient and elevated temperatures. The wear samples were prepared by metallurgical hot pressing. Wear tests were carried out on a general purpose wear testing machine having a heating unit and pin-disc sample configuration. The counterface material was prepared from Al₂O₃ ceramics. The tests were carried out at room temperature (RT), 200 ℃ and 600 ℃. The effects of temperatures on the tribological properties were determined by using optical microscopy, and X-ray diffractometry. The results show that at room temperature the worn surfaces of the alloys are characterized by mild scuffing and micro cracks, the action of nano-crystal structural wear debris on the worn surfaces is responsible for the reduction of friction. At 200 ℃, the friction coefficient is the highest. The worn surfaces of the alloys are adhesive and oxidative. At 600 ℃, the friction coefficient is reduced due to the effect of the oxides, tungstates and sulfides residue on the worn surface.

The effect of aluminum, potassium and silicon (AKS) content on the high-temperature properties and microstructure of molybdenum powder, sintering product and fabricated wires were studied. The molybdenum powder was produced firstly by reduction of molybdenum oxide which is doped with K₂SiO₃ and Al(NO₃)₃∙9H₂O. Then doped molybdenum powder was cold pressed into cylindrical compact with diameter of 17 mm, and sintered in induction furnace. The microstructure of molybdenum ingots was examined by transmission electron microscopy. The results show found that the doped elements form non-crystalline phase and distribute along the interface of Mo, thus inhibit the grain growth of Mo. Finally, the sintered Mo was drawn into wires with a diameter of 0.70 mm. The formed non-crystalline particles are changed into row of fine particle during the drawing process.

For electronic packaging applications，Mo/Cu composites with volume fractions of 55%−67% Mo were fabricated by the patented squeeze-casting technology. The microstructures and properties of the Mo/Cu composites were investigated. The results show that Mo particles are homogeneous and uniformly, and the Mo-Cu interfaces are clean and free-from interfacial reaction products and amorphous layers, the densifications of the Mo/Cu composites are higher than 99%. The mean linear coefficients of thermal expansion (20−100 ℃) of Mo/Cu composites range from 7.9 to 9.3×10⁻⁶/℃ and decrease with increasing volume fraction of Mo. The experimental coefficients of thermal expansion agree well with predicted values based on Kerner’s model. The thermal and electric conductivities of Mo/Cu composites are in range of 220−270 W/(m∙℃) and 22−28 MS/m, respectively, and decrease with increasing volume fraction of Mo. The achievement of higher thermal and electric conduction is attributed to the full densities and high purity, which are obtained through the cost-effective squeeze-casting technology processes.

Kinetics of non-isothermal precipitation process and crystal growth of perovskite phase in oxidized Ti-bearing slag were investigated. The oxidized slag was obtained by blowing the air into the molten Ti-bearing blast furnace slag through a lance. The experimental results show that the cooling rate has important effect on precipitation and growth of perovskite phase in oxidized slag; the lower cooling rate is in favor of not only the increase of the volume fraction of perovskite phase, but also the growth of perovskite phase grain sizes. The particle coarsening in non-isothermal process has important effect on the crystal growth of perovskite phase. The relative volume fraction of perovskite phase could be approximately described by JMAK equation, and the experiential expression of the average crystal radius of perovskite phase was also obtained.