Papers by Author: D.Z. Yang

Abstract: Tensile properties and deformation-fracture behavior at temperatures ranging from 123K to 293K of a Ti-6Al-4V alloy sheet with a thickness of 1.5mm has been studied, and the effects of testing temperature, specimen orientation and heat-treatment were investigated. An increase in strength and a decrease in fracture strain were found with decreasing tension temperature, and the anisotropy in tensile properties was observed at room and cryogenic temperatures both in the annealed and solution treated and aged (STA) specimens. TEM examinations indicated that plastic deformation occurred within both α and β phases in the STA specimens testing at either room or cryogenic temperature. The dominant deformation mechanism varied from dislocation slip at room temperature to twinning at 123K. SEM observations showed that the amount of dimples and tearing grains on fractured surfaces of the specimens decreased as testing temperature was decreased.

Abstract: Under the simulation environment for the vacuum and heat sink in space, the changes in optical and electrical properties of transparent conductive indium tin oxide (ITO) thin films induced by radiation of protons with 100 keV were studied. The ITO thin films were deposited on JGS1 quartz substrate by a sol-gel method. The sheet resistance and transmittance spectra of the ITO thin films were measured using the four-point probe method and a spectrophotometer, respectively. The surface morphology was analyzed by AFM. The experimental results showed that the electrical and optical performances of the ITO thin films were closely related to the irradiation fluence. When the fluence exceeded a given value 2×1016 cm-2, the sheet resistance increased obviously and the optical transmittance decreased. The AFM analysis indicated that the grain size of the ITO thin films diminished. The studies about the radiation effect on ITO thin films will help to predict performance evolution of the second surface mirrors on satellites under space radiation environment.