In order to refine microstructure and improve mechanical properties, size of lamellar colonies and reinforced phase, distribution of elements, and microhardness with different solidification rates were studied by rapid solidification. Results show that microstructure morphology changes from equiaxed grain to granulated dendrites after rapid solidification. When speed of revolution increases, size of lamellar colonies decreases from 53.5 to 16.9 μm and length of TiB particles decreases from 60.1 to 20.4 μm. The B2 phase exists in lamellar colonies and at the boundary of lamellar colonies before rapid solidification and forms in lamellar colonies after rapid solidification. An increase in solidification rate increases degree of supercooling to increase number of nucleation particles which form before solidification front. The β phase incompletely transforms to the α phase and is retained in α phase after rapid solidification. The microstructure does not have enough time to transform completely and high‐temperature microstructure is retained at a higher cooling rate. Test results show that microhardness increases from 453 to 562 HV when speed of revolution increases from 0 to 800 rpm. Improvement of microhardness results from solution strengthening of Nb, Cr, and V, grain refinement strengthening and reduction of the reinforced phase of TiB.

中文翻译：

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凝固速率对Ti44Al6Nb1.0Cr2.0V0.1B0.15Y合金快速凝固组织细化和元素分布的影响

为了细化组织并改善机械性能，通过快速凝固研究了不同凝固速率下的层状菌落和增强相的大小，元素的分布以及显微硬度。结果表明，快速凝固后，组织从等轴晶转变为粒状枝晶。当旋转速度增加时，层状菌落的大小从53.5减小到16.9μm，TiB颗粒的长度从60.1减小到20.4μm。B2相在快速凝固之前存在于层状菌落中和在层状菌落的边界处，并且在快速凝固后在层状菌落中形成。凝固速率的增加增加了过冷度，从而增加了在凝固前沿之前形成的成核颗粒的数量。β相不完全转变为α相，并在快速凝固后保留在α相中。显微组织没有足够的时间完全转变，并且高温显微组织以较高的冷却速率保留。测试结果表明，当转速从0 rpm增加到800 rpm时，显微硬度从453 HV增加到562 HV。显微硬度的提高是由于Nb，Cr和V的固溶强化，晶粒细化强化和TiB强化相的还原。测试结果表明，当转速从0 rpm增加到800 rpm时，显微硬度从453 HV增加到562 HV。显微硬度的提高是由于Nb，Cr和V的固溶强化，晶粒细化强化和TiB强化相的还原。测试结果表明，当转速从0 rpm增加到800 rpm时，显微硬度从453 HV增加到562 HV。显微硬度的提高是由于Nb，Cr和V的固溶强化，晶粒细化强化和TiB强化相的还原。