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The spatial distribution of strain, misfit and threading dislocations, and crystallographic orientation in uncoalesced GaN layers grown on Si(111) substrates by maskless cantilever epitaxy is studied. The measurements revealed that the free-hanging wings are tilted upward at room temperature in the direction perpendicular to the stripes.

Dislocation structure changes of Ni-based single crystal superalloy during impulse heating up to the melting temperature are studied using polychromatic microbeam synchrotron diffraction together with electron and optical microscopy. It is found that the maximum value of the thermal gradient is observed in the heat affected zone (HAZ) near the fusion line.

Analysis of the dislocation structure in the heat affected zone (HAZ) that will enable one to define the extent of a true HAZ and improve physical processes taking place during welding and weld cooling of Ni-based alloys is discussed. Changes occurred during spot welding of single-crystal Ni-based superalloy TSM-75 is observed.

The temperature–concentration parameters defining the existence of the eutectic transformation L⇄L12+β at the Al-rich corner of the Al–Ti–Cr phase diagram have been studied. The temperature of this transformation decreases from 1275 to 1250 °C with decreasing titanium content in the alloy, and its temperature interval is at most 10 °C. The univariant eutectic transformation line L⇄L12+β was constructed, whose coordinates on the concentration triangle are defined by the equation (in at.%): CAl=95.48–3.45CTi + 0.068 (CTi)2. As a result of this transformation, periodic microstructures consisting of lamellae and fibres of the cubic L12 and β phases are produced. Transformations in the solid state which occur during cooling lead to the precipitation of intermetallic compounds from the β-solid solution: TiAlCr (structural type C14) or AlCr2 (structural type C11b). The position of the boundary at which the change of precipitating phases occurs was determined. The analysis of mechanical properties shows that the transition from single-phase L12 aloys to eutectic microstructures is accompanied by enhancement of both strength and plasticity, while retaining a high elastic modulus. [Copyright &y& Elsevier]