Релаксация напряжений несоответствия в гетероструктурах alpha-Ga-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=-/alpha-Al-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=- при образовании дислокаций несоответствия

We propose the analytical models describing misfit stress relaxation in α-Ga2O3/α-Al2O3 film/substrate heterostructures taking into account the crystal lattices anisotropy of the heterostructure materials. We consider the nucleation of misfit dislocations as a result of basal or prismatic slip in α-Ga2O3/α-Al2O3 heterostructures with various film orientations. We calculate and analyze the dependences of the critical thickness hc (film thickness above which the nucleation of misfit dislocations is favorable) on the angle ϑ between the polar c-axis and the normal to the film growth plane for α-Ga2O3/α-Al2O3 heterostructures. We demonstrate that accounting for elastic constant C14 is not critical in the considered relaxation models for the α Ga2O3/α Al2O3 heterostructures.

Механизмы возникновения напряжений в тонких пленках и покрытиях

The paper considers current conceptions of generation of mechanical stresses in epitaxial, polycrystalline and amorphous films during their growth and under different external actions. The mechanism of stress generation in geteroepitaxial films due to misfit in crystal lattices of the film and substrate is described. The relation between arising of the misfit stress in heterostructures and variation of their growth mode is shown. The mechanisms of generation of compressive and tensile stresses in polycrystalline films caused by nucleation and coalescence of islands at the beginning of their growth are considered. Different aspects of evolution of intrinsic stresses in continuous films are discussed in dependence of their deposition conditions, chemical composition, microstructure and mechanical properties. Special attention is given to consideration of generation mechanisms of intrinsic stresses in thin films concerned with formation of pint defects, incorporation of impurities and phase transformations during deposition. Factors leading to arising extrinsic stresses in thin films during their storage and operation are described in details.

Interface Structure and Mechanical Properties of 7075Al Hybrid Composite Reinforced with Micron Ti Metal Particles Using Pressure Infiltration

Micron Ti metal particles were incorporated into SiCp/7075Al composites using pressure infiltration. The interface structure between the Ti metal particles and the matrix during the casting processes were investigated. Results show that the dispersed unreacted Ti particles form mutual diffusion layer at the interface without the formation of low-temperature intermetallic phases during the solidification processes. The interaction between the micron Ti and the molten aluminum alloy is subject to the mutual diffusion coefficient of Ti–Al rather than the reaction activation energy. The tensile strength and plasticity of the composite were improved simultaneously due to the high interfacial bonding strength and released thermal misfit stress cause by the incorporated Ti metal particles.