Gum Metal stands for a group of multifunctional titanium alloys those satisfy certain special magic electronic parameters and chemical compositions. These alloys exhibit a series of unique properties, such as superplasticity and low work hardening ratio at room temperature, and high strength, nonlinear superelasticity, low elastic modulus, Invar and Elinvar behavior after severe cold deformation. The unique properties and deformation mechanism have been disputed seriously since the alloys were developed. In this paper, by integrating our research work, the progress in research of Gum Metal is reviewed from the aspects of alloy design, preparation process, properties, composition sensitivity and plastic deformation behaviors.

Large-scale hierarchical In2O3 nanostructures have been synthesized using vapor transport and condensation method without any catalyst, taking advantage of the self-assembly property and epitaxial vapor-solid (VS) growth mechanism, and were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The results show that the In2O3 nanorods are single crystals with body-centered cubic (bcc) structure, epitaxially growing along  <100>  and <111> directions. Homoepitaxial interconnections can be observed at the branched junctions, and the growth process of the nanorods arrayed on the microcrystals is a combination of “secondary nucleation” and VS process. The room-temperature photoluminescence spectrum of In2O3 nanostructures exhibited ultraviolet emission at 386 nm and blue emission at 435 nm, which can be ascribed to the near-band-edge (NBE) emission and the possible recombination of a photo-excited hole with an electron occupying the singly ionized oxygen vacancies, respectively.

Two kinds of crystal structures (Pmn21 and P42cm) of (ammonia borane) are studied using first–principles plane wave pseudopotential method based on density functional theory in this paper. It was found that the Pmn21 structure is energetically more stable than the P42cm structure at 0 K. This agrees well with the experimental observation, that lower temperature phase is the Pmn21 structure whereas the room temperature phase is P42cm structure. The structure difference between Pmn21 and P42cm phases manifests itself mainly by the variation of intermolecular bond length whereas the intramolecular bond length remains almost unchanged. Electronic state of density was calculated to identify the bonding nature of ammonia borane. The XRD and FTIR patterns of the P42cm structure were calculated, results agree well with the experimental results of AB at room temperature.

Surface modification of ZnO nanoparticle with polyvinyl acetate was conducted through–plasma polymerization process. The surface morphology and structure of the functionalized ZnO nanoparticles were investigated. The influence of surface modification on optical properties was examined. The results indicated that a uniform layer with a thickness of 3–7 nm formed on the surface of the ZnO nanoparticles. The thin layer on the surface of the ZnO nanoparticles was found to be polyvinyl acetate (PVAC). Moreover, ageing test for two years indicated that the adhesion behavior between the organic VAC and the inorganic ZnO nanoparticles was good. In marked contrast to the uncoated ZnO nanoparticles, the surface modification resulted in significant decrease of PL intensity. UV/Vis spectra revealed that the PVAC–functionalized ZnO nanoparticles show strong absorption of UV light at wavelengths between 200 and 800 nm while the optical transparency in the visible region was slightly below that of the untreated ZnO nanoparticles.

Simulation and experimental investigation of temperature field distribution and metal flow behavior of 6201 alloy were conducted in this paper. The results show that during extending rheo– extrusion process, the isothermal lines of alloy deviate to the roll side in the roll–shoe gap, and semisolid region moves down little by little with the decrease of pouring temperature. Alloy melt in the roll–shoe gap flows by Newton laminar fluid law, and the velocity decreases gradually from the roll surface to the shoe surface where the velocity reaches 0 m·s⁻¹. Alloy melt fills the extending cavity with a radial pattern layer by layer, and then it splits and concentrates. It also exhibits homogenous laminar flow. The flow velocity is maximal at the centers of the mould and the branch holes, and decreases gradually to the side wall. The flow lines on the cross section of the tube corresponding with the branch holes center and the wielding region are dense. But there is a transitional region where the flow line is sparse. The proper pouring temperature for producing 6201 alloy tube is between 750^oC  and 780^oC.

4.5%Y2O3–ZrO2, 0.6%La2O3–YSZ, 0.8%La2O3–YSZ, 1.2%La2O3–YSZ (YSZ, 0.6La, 0.8La, 1.2La) (molar fraction) composite ceramic nanopowders were prepared by co–precipitation method using ZrOCl2·8H2O, Y(NO3)3·6H2O, La2O3 as raw materials. The synthesized powders were characterized and the phase stability was investigated. The results show that the size of 0.6La particles prepared by reverse titration method is ∼20 nm, and the size of particles prepared by the straight titration method is ∼50 nm. The agglomeration of the powder prepared by reverse titration method is also smaller than that of the powder prepared by straight titration method. After calcined at 600^oC for 2 h, all of the synthesized powders showed the pure tetragonal structure; after sintered at 1200^oC  for 100  h, 0.6La, 0.8La showed the pure tetragonal structure, the cubic phase composed of both of YSZ and 1.2La and pyrochlore structure compose of 1.2La; after sintered at 1300  for 100 h, 0.6La, 0.8La, 1.2La showed the tetragonal structure, the cubic phase compose of all synthesized powders and pyrochlore structure compose of 1.2La and small fraction of monoclinic phase (∼1.5%) was formed of YSZ; after sintered at 1400^oC  for 100h, the tetragonal phase cannot keep stable, monoclinic phase compose of all the synthesized powders, the monoclinic phase content of 0.6La, 0.8La, 1.2La, YSZ is 30.5%, 32%, 35%, 46.0% respectively. The phase stability of YSZ can be modified by addition small fraction of La2O3 at 1300^oC.

The effect of pH value of NaCl solution on the corrosion and electrochemical behaviors of 3Cr low-alloy steel was investigated by electrochemical technique and SEM technique. The results showed that the pH value of NaCl solution had great effect on the structure of corrosion product. The corrosion scale had a monolayer and map cracking appears when pH=2 and 3.9. The corrosion product film had a triple structure when pH=6.5. The pH of corrosion media also had apparent effect on the electrochemical behaviors of the Cr low-alloy steel. With pH increasing, the main cathodic reaction of electrode process altered, resulting in the negative moving of the corrosion potential, and by the increasing of the charge transfer resistance, the corrosion current density decreased.

Effects of Si on the microstructure and mechanical property of 20Mn5 steel and 20Mn5Si2 steel processed by quenching and partitioning (Q&P) were investigated. The microstructure characterization and austenite fraction measurement were carried out using scanning electron microscopy and x--rays diffraction. It was found that there is much more austenite fraction in the studied medium manganese steels than that of conventional TRIP steels and steels treated by Q&P process; and under same experimental condition, the austenite fraction in 20Mn5Si2 is significantly higher and fewer precipitated carbides than that in 20Mn5 steel. It was proposed that the larger fractioned austenite in Si--medium Mn steel results in the much lower yield stress and much higher product of tensile strength to elongation than that of the medium Mn steel without Si both processed by quenching and partitioning.

α/β mutually embedded nickel hydroxide has been synthesized by chemical coprecipitation method. The microstructure and surface morphology of the prepared samples were analyzed by X–ray diffraction (XRD), Fourier transform infrared (FTIR), and scanning electron microscopy (SEM). The electrochemical performance of the prepared sample was characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and charge discharge tests. Compared to the pure β nickel hydroxide, the α/β mutually embedded nickel hydroxide shows a higher electrochemical reaction activity, lower electrochemical reaction impedance, higher discharge capacity, and higher discharge voltage. Moreover, α/β mutually embedded nickel hydroxide has better cyclic performance.

Protective composite coatings were obtained on a magnesium alloy by micro–arc oxidation (MAO) and sol–gel technique. The cross–section morphologies and composition of the MAO coating and composite coatings were analyzed by scanning electron microscopy (SEM) and energy dispersive X–rays (EDX). The phase structure of the composite coatings was analyzed by X–ray diffractometer (XRD). The corrosion resistance of MAO coating and composite coatings in a 3.5% (mass fraction) NaCl solution was evaluated by potentiodynamic polarisation measures. The results show that SiO2–ZrO2 sol can effectively seal the micropores in the MAO coating, and the composite coatings are more compact and have good adhesion. The composite coatings are composed of MgO, MgAl2O4, SiO2 and ZrO2. The corrosion resistance of the sample with composite coatings is enhanced significantly.

A new type of Fe–Cr–Ni–Co overlaying alloy was prepared by argon tungsten–arc welding (TIG) on 304stainless steel, after cooling to room temperature, the weld cladding layer was remelted by TIG. The effect of remelting on the resistance to cavitation erosion property was investigated and the result was compared with that of 304 stainless steel and weld–cladding layer. The alloy layer was analyzed by weight loss analysis, scanning electron microscopy (SEM) and X–ray diffractometer (XRD). Results indicating that the grain size in remelting layer was smaller. The resistance to cavitation erosion property of overlaying and remelting layer was better than that of 304 stainless steel and remelting layer is even better than that of overlaying. Phase transformation from austenite to martensite happened in the cavitation erosion process, which absorbed the energy of cavitation erosion and delayed the process of cavitation erosion. The refined grains by TIG remelting process in the overlaying alloy prevented the development of cracks and enhanced the cavitation erosion resistance property effectively.

The microstructure and mechanism of fatigue crack initiation of 2024–T3 and 2524–T34 Al alloys were investigated. Four–point bending and tension –tension fatigue tests on the tested alloys with a frequency of 15 Hz, R=0.1 along the rolling direction were conducted at room temperature. It was found that the flat grain was elongated along the rolling direction, showing the laminar grain structure. The amount of coarse and irregular particles and the density of secondary particles  distributed in 2024 were much higher than that in 2524. Particles in 2524 distributed stripped along the rolling direction. The majority of fatigue cracks of 2524 were initiated on the coarse β phase second particle, containing Fe, a few of them formed on sites of material defects or slip bands. The intrusion and extrusion induced by slip band in the Al cladding layer provided principal fatigue crack initiation sites for 2024 and 2524 Al–cladding aluminum alloys.

Diamond–like carbon (DLC) films were prepared on the surface of 45 steel substrates by the radio–frequency plasma enhanced chemical vapor deposition (rf–PECVD) technique. The bond structure, surface morphology and microstructure of DLC film were characterized with a laser Raman spectroscopy (Raman), X–ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and atomic force microscope (AFM). The hardness of DLC film was determined by the tribo–indenter in − situ nano–mechanical test system. Tribological behaviors of DLC film against GCr15 steel were performed using a UMT–  friction and wear tester under the various normal loads and sliding speeds. And the wear mechanisms were also analyzed. The experimental results showed that the thin film deposited on the surface of 45 steel has the typical structural characteristics of DLC film. The surface of DLC film composes of the compact nano–particles, which has the higher hardness than that of the 45 steel substrates. Under the different tribological conditions, DLC film showed the higher wear–resistance and lower friction coefficient compared with the 45 steel substrates. Especially in the high–speed and low–load conditions, the friction coefficient was lower than 0.008.

SiO2 sol was prepared by hydrolyzing of organic alkoxide, and the dipping–costing method was employed to prepare the SiO2 layer onto micro–arc oxidation(MAO) coating of AZ31B magnesium alloy. The sol structure, differences in micro–morphology and corrosion resistance between ceramic coating and composite coatings were investigated. The results show that SiO2 sol immersed into the micro pores on the surface of MAO coating and formed an inorganic SiO2 layer. The corrosion potential of composite coatings which composed of ceramic coating and SiO2 layer increased, and the corrosion current density reduced by about 2 orders of magnitude comparing with the ceramic coating. The molar ratio of TEOS to H2O affects the structure of SiO2 layer seriously and the action of suppressing the corrosion medium of SiO2 layer.

The near–infrared luminescence properties of Ni2+ doped the near–stoichiometric LiNbO3 (SLN) single crystals have been investigated. Under a laser diode excitation source at 980nm, a near–infrared luminescence in Ni2+:SLN single crystals centers at 1087 nm with its FWHM about 72 nm was found. The fluorescence decay properties of crystal were measured, and the fluorescence lifetime of Ni2+:SLN single crystals was as long as 240 μs even at room temperature. The observed near–infrared fluorescence can be attributed to the 3T2g(3F) →3 A2g(3F) transition of Ni2+ in octahedral sites.

(Ti, Al, Zr)N multi–component hard films with N–gradient distributions were prepared by multi arc ion plating (MAIP) technology using the combined pure Zr and Ti–Al alloy targets. The surface and cross–fracture morphology, the surface compositions and the phase structure of the as–deposited films were observed and measured. The effects of bias voltage on the film quality, phase structure, the micro–hardness, the adhesion between film and substrate and the thermal shock resistance were investigated. In comparison with TiN, (Ti, Al)N and (Ti, Zr)N films, the as–deposited (Ti,Al,Zr)N films from the combination of pure Zr and Ti–Al alloy targets exhibited higher micro–hardness values even up to HV6000. Each of the as–deposited films has very high adhesion strength, in terms of critical load, larger than 180 N. The good heat shock resistance was also reached for each of the as–deposited films.

A novel method for grafting azo-groups onto the surface of SiO2 nanoparticles to prepare SiO2-initiator by the esterification reaction under the mild conditions, has been developed. The monomers as styrene or methyl methacrylate was polymerized using azo-group bounded SiO2 as an initiator, and then polystyrene or poly(methyl methacrylate) chains grow out of the surface of SiO2 nanoparticles. Results show that polymer grafted onto the surface of SiO2 nanoparticles accounts of ca. 45% (mass fraction)of SiO2. As a result, the average particle size increases from 80 nm to 100 nm upon the polymer grafting. Consequently, the core-shell composite particles with polymer on the outside and SiO2 in the core are obtained.

Pr-doped Ba ferrite composite film was prepared by a sol-gel method and an in situ polymerization method, respectively. The structure, morphologies, magnetic properties and microwave absorption properties of the samples were characterized using X-ray diffractometer (XRD), Fourier transform infrared spectrometer (FTIR), scanning electron microscope(SEM), vibrating sample magnetometer (VSM) and magnetic vector network analyzer. The results show that the saturation  agnetization (Ms) and the remanent magnetization (Mr) of the composite film are lower than that of Ba Ferrite film, but the coercivity force (Hc) of the composite film is higher than that of Ba Ferrite film. Pr doped Ba ferrite/ polypyrrole composite film has both dielectric loss and magnetic loss, which is beneficial to widen microwave band and improve microwave absorption properties.

Organic–inorganic hybrid mesostructures have been prepared using 1,2–bis (trimethoxysilyl) ethane (BTME) and poly(methylhydrogen)siloxane (PMHS) as starting precursors via a facile sol-gel synthesis pathway in the absence of traditional surfactants. The dependence of structural properties on the preparation parameters was investigated by solid state29 Si MAS NMR, high-resolution TEM, low temperature N2–adsorption/desorption isotherms, thermo-gravimetric analysis (TGA–DTA), Fourier transform infrared spectrophotometry (FT–IR) and water contact angle measurement. Characterization results showed that the hybrid material prepared under optimal conditions possesses stable framework structure and developed porosity with high specific surface area and pore volume of 1076 m2/g and 1.03 cm3/g, respectively.

La2O3 doped Ba0.55Sr0.45TiO3/Mg2TiO4 microwave composite ceramics were prepared by traditional solid-state reaction, and the influence of La2O3 doping on microstructure, dielectric properties and tuning was investigated. The results show that La3+ enters BST lattices when the mass fraction of La2O3 reach 1.2%, and La3+ doped sample can prevent the change of the chemical valence of Ti in BST/Mg2TiO4 composite system from +4 to +3. Mg2TiO4 and La2O3 doping can reduce the dielectric constant and microwave loss separately. The 1.2% La2O3 doped sample has the best properties: dielectric constant 52; tanδ 0.0011 (10 GHz), and the tunability 13.4% (3 kV/mm).