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针对高功率条件下激光立体成形Ti-6Al-4V合金组织特征展开研究,揭示高功率条件下组织形成机理,并对比分析了高功率与中/低功率条件下组织形成的差异及原因。结果表明:由于高功率条件下具有更低的温度梯度和更高的凝固速度,激光立体成形Ti-6Al-4V合金的宏观组织由粗大的柱状晶、竹节状的小柱状晶和等轴晶三部分组成,并且沉积层之间存在层带;而中/低功率条件下只有贯穿多个沉积层呈外延生长的粗大的柱状晶。高功率条件下层带内典型微观组织是由大量的魏氏α集束组成,而层带间为α板条编织成的网篮状组织,并且部分α相球化成等轴状。与中低功率条件下典型组织相比,高功率条件下α板条长宽比明显减小,不存在针状α。
The microstructure of Ti-6Al-4V alloy was studied under high power conditions. The mechanism of the formation of Ti-6Al-4V alloy under high power condition was revealed. The differences of the formation of Ti-6Al-4V alloy under high power and medium / low power were also analyzed. The results show that due to the lower temperature gradient and the higher solidification rate under high power, the macrostructure of Ti-6Al-4V alloy is composed of coarse columnar, small columnar bamboo-like and equiaxed Part of the sedimentary layer, and the lamellae exist between the sedimentary layers; while the middle / low power conditions, only through the deposition of multiple epitaxial growth of large columnar crystals. The typical microstructure in the belt under high power is composed of a large number of Wesselphase α bundles, while the belt is woven into a basket of α-lath, and part of the α phase is spheroidized into an equiaxed shape. Compared with the typical tissue at medium and low power, the aspect ratio of α lath significantly decreased under high power condition, and there was no acicular α.