III-V compound semiconductors, specifically gallium arsenide and gallium phosphide, have potential application as high-speed windows and domes for broadband infrared transmission, especially the 8- to 12-μm region. Their application as very high speed domes is made possible by enhancing their mechanical properties, particularly fracture toughness. This work describes the process used to hot press GaAs and GaP powders to near theoretical densities. High resistivity materials were used to form the powders in simple milling techniques. Near theoretical densities were achieved at pressures of 30,000 to 40,000 psi and temperatures approximately two-thirds of the material melting point. Morphological studies using Nomarski microscopy, SEM, and TEM of fracture surfaces and polished and etched surfaces reveal significant dislocation loops, subgrain boundaries and texturing consistent with an increased fracture toughness in the hot pressed powders. The morphology and force versus displacement data verify the mechanism of densification to be plastic deformation. Sample disks of the hot pressed powders were fabricated to a 1-inch diameter and 1/8-inch thickness. The hot pressed GaAs showed 8- to 12-μm transmission to 16 percent limited by light scattering, probably caused by residual porosity. The hot pressed GaP has not shown any transmission, probably because of light scattering from residual porosity and absorption caused by a Ga-rich phase from decomposition of the powder surfaces during pressing.
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