Orientation-tuning in self-assembled heterostructures induced by a buffer layer

Orientation tuning of heterostructures with a nano-plate configuration was demonstrated by a complex in-plane strain and ledge growth mechanism.

The Effect of Heat Treatment on the Microstructure and Properties of FeAl+Cr

ABSTRACTMicrostructural studies were performed on an alloy of composition Fe45Cr5Al50 heat treated at 950°C and oil-quenched and then given isothermal annealing treatments for times up to 200 hours at either 400°C or 500°C. The observed microstructures were correlated with variations in hardness during isothermal annealing. It was deduced that the thermal vacancies retained following the initial heat treatment are removed relatively rapidly from the lattice, which leads to an initial drop in hardness. However, during prolonged annealing, the coarsening of bothFeAl2 particles and a disordered a(Fe,Cr) phase leads to further softening. It was also deduced that the chromium atoms, which remain in solution, are effective solute strengtheners. The a(Fe,Cr) phase, which is coherent with the B2 matrix, appears to coarsen by a ledge growth mechanism.

High Resolution In Situ TEM Studies of Silicide-Mediated Crystallization of Amorphous Silicon

ABSTRACTWe report in situ high resolution transmission electron microscopy studies of NiSi2-Medi-ated crystallization of Amorphous Si. Compared to conventional solid phase epitaxy of (111) Si, an enhancement of the growth rate by three orders of magnitude was observed and high quality twin-free needles of <111> Si were formed. Crystallization occurred via a ledge growth mechanism at the epitaxial Type A NiSi2/crystalline Si (111) interface. A Model for NiSi2-Mediated crystallization of Amorphous Si involving the passage of kinks along <110> ledges at the NiSi2/crystalline Si (111) interface is proposed.

Equilibrium And Non-Equilibrium Metal-Ceramic Interfaces

ABSTRACTMetal-ceramic interfaces in theimodynamic equilibrium (Au/ZrO2) and non-equilibrium (Au/MgO) have been studied by TEM and HREM. In the Au/ZrO2 system, ZrO2 precipitates formed by internal oxidation of a 7%Zr-Au alloy show a cubic ZrO2 phase. It appears that formation of the cubic ZrO2 is facilitated by alignment with the Au matrix. Most of the ZrO2 precipitates have a perfect cube-on-cube orientation relationship with the Au matrix. The large number of interfacial steps observed in a short-time annealing experiment indicate that the precipitates are formed by the ledge growth mechanism. The lowest interfacial energy is indicated by the dominance of closed-packed {111} Au/ZrO2 interfaces. In the Au/MgO system, composite films with small MgO smoke particles embedded in a Au matrix were prepared by a thin film technique. HREM observations show that most of the Au/MgO interfaces have a strong tendency to maintain a dense lattice structure across the interfaces irrespective of whether the interfaces are incoherent or semi-coherent. This indicates that there may be a relatively strong bond between MgO and Au.