We have investigated the effects of O on the structure and mechanical properties of NiAl intermetallics using a first-principles pseudopotential total-energy method based on the density functional theory with the generalized gradient approximation. We found that the impurity O atom can either replace Ni atom or go into the tetrahedron interstitial site depending on the surrounding environment. In both cases, O tends to form an Al2O3-like tetrahedron structure with its nearest Al or Ni atoms, leading to the formation of the stronger O–Al bond containing covalent component. We demonstrate that the presence of O will cause an increase of the brittleness and a decrease of the ductility of NiAl based on the calculated elastic constants and the empirical criterions for both substitutional and interstitial cases. Our calculations provide a way to suppress the negative effect of O by adding the alloying element with lower electronegativity than that of Al.

High-strength, heat- and oxidation-resistant low density Ti–Ni–Al intermetallic alloys have recently attracted attention competing with some conventional high temperature structural superalloy such as Ni-based superalloy. In the present study, the mechanical properties of Ti-rich Ni50−xTi50Alx (x = 6,7,8,9) alloys were examined by compression tests at room temperature and at high temperature from 400 °C to 800 °C. X-ray diffraction, scanning electron microscopy as well as microhardness tester were utilized to characterize the microstructure as well as the structural evolution with the increasing Al additions. The systematic analyses of the mechanical behavior were made according to compression test at different temperatures. A yield stress of 1800 MPa and more than 10% of compression strain were achieved at room temperature; and a yield stress of 400 MPa at 800 °C. It is suggested that controlling the shape, the volume percent and the distribution of second phases in the matrix is most important to obtain good mechanical properties in these alloys. The strengthening mechanism of aluminum addition on the mechanical properties was discussed systemically according to the microstructure evolution and solution hardening and precipitation hardening upon Al addition.

In order to improve the oxidation resistance of Nb–Si system intermetallics, silicide was deposited on the substrate by molten salt or by pack cementation, and Cr was deposited by pack cementation. Phase and microstructure were observed by scanning electro microscope (SEM), X-ray diffraction (XRD) and energy diffusion spectrum (EDS). It was found that phases of NbSi2, CrSi2, Cr2Nb were formed. The result showed that the high temperature oxidation resistance of the Nb–Si system intermetallics will be improved by applying the Cr doped Si coatings. Maybe it was attributed by the formation of SiO2 and Cr2O3 which could prevent the penetration of oxygen into the inner coatings and the substrate.

The phase stability of lanthanum cerium oxide (La2Ce2O7), which is stable up to 1400 °C, and the thermal expansion coefficient of La2Ce2O7 doped with Ta2O5 or WO3 were studied. The thermal expansion coefficient of La2Ce2O7 below 400 °C was increased by adding more CeO2 or doping with either Ta2O5 or WO3.

Martensite aging results in martensite stabilization in single-phase Ni54Mn25Ga21 alloy; however, it has no effect on the transformation temperatures of dual-phase Ni58Mn25Ga17 alloy. The reverse martensitic transformation temperatures of both alloys decrease sharply with the increase of aging time and then graduate to a constant level after austenite aging.

Bulk material and coatings of Lanthanum–Cerium Oxide (La2Ce2O7) with a fluorite structure were studied as a candidate material for thermal barrier coating (TBC). It has been showed that such material has the properties of low thermal conductivity about four times lower than YSZ, the difference in the thermal expansion coefficient between La2Ce2O7 and bond coat is smaller than that of YSZ in TBC systems, high phase stability between room temperature and 1673 K, about 300 K higher than that of the YSZ. The coating prepared by electron beam physical vapor deposition (EB–PVD) showed that it has good thermal cycling behavior, implying that such material can be a promising thermal barrier coating material. The deviation of coating composition from ingot can be overcome by the addition of excess La2O3 during ingot preparation and/or by adjusting the process parameters.

Al–Cu–Fe–Cr quasicrystalline coating was deposited on a substrate of stainless steel by low-pressure plasma spraying (LPPS) method. The corrosion behavior of such coating was studied by polarization in 1 mol/l H2SO4 and 0.1 mol/l NaOH solutions at room temperature. The polarization curve shows that LPPS Al–Cu–Fe–Cr quasicrystalline coating can turn to passive state both in 1 mol/l H2SO4 solution and in 0.1 mol/l NaOH solution. The corrosion resistance of the coating is poorer than that of bulk quasicrystal in 0.1 mol/l NaOH solution. Also in strong alkaline solution the corrosion resistance of the coating is much poorer than single-phase austenitic stainless-steel 1Cr18Ni9Ti. In the later period of polarization, the Al2O3 layer formed on surface of the coating is destroyed by localized corrosion.

In the present study, thermal barrier coatings (TBCs) with two layered bond coat of MCrAlY and MCrAlY–Si were prepared by means of electron beam physical vapor deposition (EB-PVD) on Ni3Al based alloy IC6 in order to suppress the diffusion of Mo contained in the alloy. For the bond coat without Si addition, Mo content near the surface was higher than 7 wt% after isothermal oxidation at 1373 K for 60 h and 12.5 wt% after thermal cycling tested at 1373 K for 300 h (600 cycles). However, in the two layered bond coat with MCrAlY and MCrAlY–Si, only 0.4 wt% Mo was detected after isothermal oxidation at 1373 K for 100 h and about 0.6 wt% after thermal cycling tested at 1373 K for 400 h (800 cycles). With the use of two layered bond coat of MCrAlY and MCrAlY–Si, the diffusion of Mo was effectively blocked and the thermal cycling behavior of the TBCs has been greatly improved.

Phase transformation behaviors and mechanical properties of TiNiMo shape memory alloys have been investigated. It was found that the martensite transformation temperatures decrease drastically with increasing Mo content, while the R phase transformation temperatures vary slightly. Ti50Ni49.5Mo0.5 and Ti50Ni49Mo1.0 alloys exhibit good workability with lower σy followed by drastically plastic deformation due to slip. Ti50Ni48Mo2.0 alloy with moderate martensite transformation temperature, much higher yield strength and fracture strength measured to be 589 and 799 MPa, respectively, as well as Ti50Ni48.5Mo1.5 alloy with appropriate martensite transformation temperature and excellent mechanical properties, are very promising for use as coupling materials.

NiCoCrAlY+(6–8 wt%)Y2O3 stabilized ZrO2(YSZ) two-layer thermal barrier coatings (TBCs) were deposited by electron beam physical vapor deposition on Ni3Al or Ni-base superalloy and their high temperature fatigue behavior was investigated experimentally and computationally. It has been found that the pre-treatment of the bond coat has greatly improved the thermal cyclic lifetime of TBCs with respect to those without pre-treatment. The lifetime is limited by the existence of interface between bond coat and top coat, and smoothing the interface can also improve the thermal cyclic lifetime. When the roughness of the interface changed from 3.76 to 0.82 μm, testing lifetime increased from about 500 (1000 cycles) to 700 h (1400 cycles), and the adhesive strength of the interface increased from 3.5 to 4.7 MPa m1/2 estimated from the result of surface Rock-well hardness testing. Cracks occurred in the thermally grown oxide (TGO) layer are considered to be the main reason for the failure of two-layer TBCs. It has been found that with pre-oxide layer thickness increasing from 1.0 to 3.0 μm, the growth rate of TGO increased during thermal cyclic testing and the thermal cyclic lifetime of TBCs decreased from 730 to 450 h. The lower lifetime was caused by the co-action of larger internal stress resulted from thicker TGO layer and the fatigue of the TGO layer. Finite element method (FEM) analysis showed that large tensile stress was introduced at the beginning of rapid cooling process, resulting in the spallation of top coat from bond coat. Ab initio calculation was carried out to evaluate the binding energy of the interface of bond coat and ceramic top coat, and FEM models were used to investigate stress and strain states in TBCs during thermal shock process as a function of cooling rate. The results showed that ZrO2/Ni interface exhibits nonmetallic properties, and that the chemical bonding in ZrO2/Ni is covalent–ionic in nature. The calculation of binding energies between both Ni and O and Zr and O indicates that the binding energy of Ni and O is larger than that of Zr and O, which is helpful to investigate the failure mechanism of thermal barrier coatings.

Study on Ni–Mn–Ga ferromagnetic shape memory alloys recently keeps active. Intermartensitic transformation was found. Magnetic field enhanced phase transformation strain was discovered, and achieved up to 4%. Fifteen percent super high strain induced by variant reorientation under stress was obtained in non-modulated martensite. Six percent large magnetic field induced strain was achieved, and the temperature dependence was investigated in 5-layered martensite single-variant Ni–Mn–Ga alloys. Several other systems of magnetic shape memory alloys and high temperature shape memory alloy Ni–Mn–Ga are also reviewed.