0.5～22μm宽光谱ZnSe单晶窗口制备

采用电阻加热水平物理输运法对生长ZnSe晶体的原料进行提纯,使其纯度达到5N(99.999%).利用Bridgman单晶生长方式生长ZnSe晶体,所得晶体尺寸为φ35 mm×100 mm.在对晶体性能进行分析后,寸晶体进行切割、研磨、抛光,获得粗糙度为光学四级的晶体器件.晶体抛光后未镀膜,在0.5～22μm的波艮范围,平均透过率达到60%以上.晶体镀膜后,在波长为10.6μm处的透过率可达98%以上.     

Crystal preferential orientation ofAl-1.0%Si alloy in continuous unidirectional solidification process

Al-1.0%Si alloy rods containing unidirectional microstructures were fabricated by continuous unidirectional solidification （COS） process. The crystal growth orientation evolution of Al-1.0%Si alloy in CUS process was studied. The microstructure was observed and the orientation results examined by electron back scattering diffraction（EBSD） indicate that at the beginning of COS process the crystals grow along a certain preferred orientation, （100）direction, but there are also other growth directions deflecting from this preferred orientation. It is found that as directional solidification continues, the crystals with high growth speed remain and those with low growth speed vanish. The crystal preferred orientation tends to be （100）direction in competition growth process. Namely, the （100） fiber texture oral-1.0%Si alloy rod becomes stronger in the stable directional solidification establishing process. When the solidification parameters remain stable, the crystal growth orientation also obtains in steady state. Once the technological parameters fluctuate, the stray crystals deviating from the preferred orientation appear. After the process of competition growth the crystals regain strong preferred orientation. The orientation distribution function（ODF） results also testify the above conclusions.