The invention provides a preparation method of a
metal material with a multi-phase heterostructure, which comprises the following steps of: weighing
metal raw materials according to the components of the
metal material,
smelting to obtain
molten metal, carrying out electric
pulse treatment on the
molten metal to obtain a melt, carrying out directional
crystallization on the melt to obtain a cast
ingot with an inclined splayed columnar
crystal structure, carrying out
hot working to obtain a blank, and carrying out heat treatment on the blank to obtain the metal material with the multi-phase heterostructure. And then the blank is subjected to cold
machining treatment, a cold machined part is obtained, finally, the cold machined part is subjected to micro-area electric treatment, and the metal material with the multi-phase heterostructure is obtained. According to the method, a structure of a core columnar
crystal and an edge equiaxed
crystal is obtained through
hot working, the hard outside and the tough inside are achieved, then more
dislocation and deformation twin crystals are obtained through large-deformation cold working treatment, finally, the material is subjected to
zoning treatment through micro-zone electric treatment, a structure with a
softening zone and a hardening zone alternated is obtained, and tough alternation is achieved; under the
synergy of the process, the multiphase heterostructure metal material which is hard outside and tough inside and has excellent mechanical properties is obtained, and the
toughness of the multiphase heterostructure metal material is alternated.