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A mixture of ferrotitanium and sucrose was heated to carbonise the sucrose, so the ferrotitanium particles were bound by the carbon obtained from the pyrolysis of sucrose. Then a Fe-Ti-C composite powder was made for reactive thermal spraying, which could avoid separation of Ti and C during spraying. The carbon is a reactive constituent as well as the binder in the composite powder. While this powder was used to deposit cermet coating by plasma spraying, a mass of TiC particles were in situ synthesised and uniformly distributed within metallic matrix. Average microhardness and surface hardness of the TiC-Fe coating are about 1672·5 HV0·2 and 91·4 HR(15 N) respectively. Adhesive strength value of the coating reaches 61·86 MPa. Finally, the cermet coating has good wear resistance performance. [ABSTRACT FROM AUTHOR]

Carbon fibre reinforced SiC (Cf/SiC) was successfully joined to Ti alloys with Cu-Ti-C mixed powder by brazing. Microstructures of the brazed joints were investigated by SEM, EDS and XRD. The mechanical properties of the brazed joints were measured by a mechanical testing machine. The results showed that the performed joints have dense bonding layers reinforced by residual graphite and in situ synthesised TiC from the reaction of C and Ti in the bonding layers. The composite brazing layers relaxed the thermal stress of the joints effectively. These characteristics were beneficial to the joints, of which the shear strength was remarkably higher than the optimal shear strengths of the joints brazed with pure Cu-Ti. [ABSTRACT FROM AUTHOR]

Abstract: TiN films were prepared by ion beam assisted deposition (IBAD) method under different temperatures and ion energies. Microstructure characterization by X-ray diffraction (XRD), atomic force microscopy (AFM), scanning and transmission electron microscopy (SEM and TEM) confirmed that the nitride films were nanocrystalline in size and composed of grains with grain sizes ∼20 nm. Textures of the films were studied by XRD pole figure measurements. Residual stress was determined by the modified sin2 ψ method using grazing incidence XRD. Hardness of the thin films was measured by nanoindentation. It is found that nanoindentation measurement cannot reflect the variation of residual stress. Nanohardness of the samples also displayed insignificant relationship with texture. Since the dislocation activity is retarded due to nanograin structure, the geometrical strengthening via texture control or Hall–Petch relationship is no longer applicable. Therefore, grain rotation or grain boundary sliding may be the deformation mechanisms for nanocrystalline thin film. The contradictory relationships between hardness and preferred orientation were also clarified. [Copyright &y& Elsevier]

Self-assembled In1-xMnxAs quantum dots (0.19≤=x≤=0.45) have been grown on GaAs (100) substrates by low-temperature molecular beam epitaxy. The microstructure analysis revealed that the uniformly distributed In1-xMnxAs dots have a zinc blende structure as x≤=0.38. Furthermore, all samples exhibit ferromagnetic state at 5 K, and their Curie temperatures range from 260 to 340 K varying with x. These (In, Mn)As quantum dots are promising for room-temperature spintronic devices [ABSTRACT FROM AUTHOR]

An atomically flat and uniform reaction layer of Mn(Ga)As was found to self-organize at the (Ga,Mn)As/IrMn interface by postannealing. The Mn(Ga)As layer exhibits strong ferromagnetic characteristics up to the measured 300 K. In particular, the manifested horizontal shift of field-cooled hysteresis loops shows a clear signature of exchange bias attributable to the exchange coupling between IrMn and Mn(Ga)As. Implication from composition analyses, exchange-bias effect, and thickness dependence of the Mn(Ga)As layer versus annealing conditions is also discussed. [ABSTRACT FROM AUTHOR]

The effects of low-temperature (210 °C-290 °C) annealing on the microstructure, lattice constant, and magnetic properties of (In0.52Al0.48)0.91Mn0.09As grown by low-temperature molecular-beam epitaxy were studied. The results show that low-temperature annealing has little influence on the crystalline structure and interface quality of (In0.52Al0.48)0.91Mn0.09As epilayer. In contrast, both the lattice constant and Curie temperature of (In0.52Al0.48)0.91Mn0.09As are found to be strongly dependent on the annealing temperature. The lattice constant linearly decreases with increasing annealing temperature; while the Curie temperature increases with increasing annealing temperature up to 250 °C, and then abruptly decreases upon further annealed at 270 °C and 290 °C. [ABSTRACT FROM AUTHOR]