The article reports on the enhanced hardness of nanocomposite coatings, their thermal stability, protection of the substrate against oxidation at temperatures above 1000 °C, X-ray amorphous coatings thermally stable above 1000 °C and new advanced hard nanocomposite coatings with enhanced toughness which exhibit (i) low values of the effective Young's modulus E ⁎ satisfying the condition H/E ⁎  > 0.1, (ii) high elastic recovery W e  ≥ 60%, (iii) strongly improved tribological properties, and (iv) enhanced resistance to cracking; here E ⁎  = E(1−ν 2 ), E is the Young's modulus and ν is the Poison's ratio. At the end trends of next development of hard nanocomposite coatings are briefly outlined.

Hard nanocomposite coatings: Thermal stability, oxidation resistance and toughness

Magnetron sputtering of films with controlled texture and grain size

A realistic n -body Ni-Ti potential is derived and applied in molecular dynamics simulation for studying the lattice stability of the terminal solid solutions and an intermetallic compound of B2 NiTi phase. It is found that when the solute contents are increased beyond two respective critical values of 15 at% of Ni and 38 at% of Ti, the crystalline lattices of the solid solutions become unstable and transform into amorphous states, suggesting that a glass-forming range of the system is from 15 to 62 at% of Ni. In the case of B2 NiTi compound, a crystalline-to-amorphous transition can result from the introduction of either a certain amount of chemical disordering or a compositional shift from its exact stoichiometry. In addition to the B2 NiTi phase, the simulation results also give some insight concerning the phase transition behaviour upon irradiation for the Ni3 Ti and NiTi2 intermetallic compounds.

Lattice stability of some Ni-Ti alloy phases versus their chemical composition and disordering

A dodecagonal quasicrystalline phase was grown in nano-sized Ag-Pt multilayers upon solid-state reaction and the existence of the respective metastable state in the Ag-Pt system was also confirmed by ion-beam mixing experiments. The major driving force for intermixing between the nano-sized Ag and Pt layers, as well as for the crystal-to-quasicrystal transition, was thought to be the interfacial free energy, which elevated the initial Ag-Pt multilayers up to an energetic state corresponding to the dodecagonal phase.

Formation of a dodecagonal phase in the nano-sized Ag-Pt multilayers upon solid-state reaction

In the present review article, firstly, the experimental observations of the binary metallic glass formation by various glass-producing techniques are briefly summarized. Secondly, a detailed discussion is presented concerning the concepts of the glass-forming ability and glass-forming range (GFA/GFR) of a binary metal system. Meanwhile, some of the proposed empirical criteria or rules for predicting the binary metallic glass formation are discussed and compared with the experimental observations. Thirdly, it is proposed to take the interatomic potential of a binary metal system as the starting base to develop an atomistic theory capable of predicting the binary metallic glass formation. Accordingly, eight binary metal systems are selected as representatives to cover the various structural combinations as well as various thermodynamic characteristics. The n-body potentials of eight representative systems are then constructed with the aid of ab initio calculations. Applying the constructed and proven realistic n-body potentials, a series of molecular dynamics simulations are carried out. In the simulations, solid solution models are employed to compare the relative stability of the solid solution versus its competing disordered counterpart (i.e. the amorphous or metallic glass phase) as a function of the solute concentration. Finally, based on the realistic interatomic potentials, molecular dynamics simulations not only reveal the physical origin of the binary metallic glass formation, but also quantitatively determine, for each system, an alloy composition range, within which the disordered state is energetically favored, thus leading to establish the atomistic theory capable of predicting the GFR, i.e. the quantitative GFA, of the binary metal systems.

O. Jin

Papers

Formation and Theoretical Modeling of Non‐Equilibrium Alloy Phases by Ion Mixing