Rapid dendritic growth kinetics of primary phase within supercooled Zr-V alloy at electrostatic levitation state.

• Growth kinetics of primary β-Zr dendrite phase and eutectic phase in undercooled liquid Zr-V alloy were detailed analyzed. • The maximum undercoolings exceeding the empirical threshold undercooling 0.20 T L for homogeneous nucleation were achieved. • The metastable solidification pathway with different undercooling was researched. • A critical undercooling for eutectic morphology transition was obtained for hypoeutectic Zr 70 V 30 alloy. • The Vickers hardness tests prove that undercooling control is an effective method to regulate the mechanical properties of Zr-rich Zr-V alloys, and the maximum adjustable range of hardness could reach 10%–20%. The liquid Zr 100− x V x (x = 8.6, 16.5, 30) alloys were undercooled to the maximum undercooling of 364 K (0.18 T L), 405 K (0.21 T L), and 375 K (0.21 T L), respectively, by using electrostatic levitation technique. The Zr 91.4 V 8.6 and Zr 83.5 V 16.5 alloys present only one recalescence during liquid/solid phase transition, while the Zr 70 V 30 alloy presents a transformation from two recalescence to one recalescence phenomenon with a critical undercooling of approximately 300 K. According to the LKT/BCT model, the calculated results of the primary β-Zr dendrite growth velocity in undercooled liquid Zr 91.4 V 8.6 and Zr 83.5 V 16.5 alloys agree well with the experiments. The velocity inflection points at 119 K of Zr 91.4 V 8.6 alloy and 201 K of Zr 83.5 V 16.5 alloy could be explained by the competition between solutal undercooling control and thermal undercooling control modes. For Zr 70 V 30 alloy solidified in the P1 with twice recalescence, a critical second undercooling of 253 K and corresponding undercooling of 65 and 244 K are obtained. When the undercooling is in the range of 65–244 K, the second undercooling would be greater than 253 K, and the residual liquid phase would solidify into anomalous eutectic microstructure for Zr 70 V 30 alloy. The Vickers hardness of Zr 100− x V x (x = 8.6, 16.5, 30) alloys all show a quadratic relationship with undercooling. Under electrostatic levitation condition, the mechanical property of Zr-V alloys could be significantly regulated through solidifying the alloys at different undercoolings. [Display omitted] [ABSTRACT FROM AUTHOR]