The physical mechanisms of crystal nucleation and dendritic growth within undercooled niobium were systematically studied by electrostatic levitation and molecular dynamics methods. The maximum undercooling was achieved as 454 K (0.16T(m),), while the hypercooling limit was determined as 706 K (0.26T(m)). The undercooling probability displayed Poisson distribution and indicated the occurrence of heterogeneous nucleation. The calculated critical nucleus size reduced rapidly with undercooling and the solid-liquid interface energy was deduced to be 0.367 J m(-2). In addition, the dendritic growth velocity of pure niobium exhibited a power relation versus undercooling, and reached 41 m s(-1) at the maximum undercooling. (C) 2017 Published by Elsevier B.V.