Functionally graded materials with grain-size gradients and heterogeneous microstructures achieved by additive manufacturing

Abstract

In this work, 316L/CuCrZr functionally graded materials were prepared by laser powder bed fusion. Not only the strong bonding of 316L and CuCrZr was achieved, but more importantly, the grain-size gradients and heterogeneous microstructures were introduced into the samples. The gradient microstructure was characterized by ultrafine equiaxed grains sandwiched between micron-scale columnar grains. The dual-scale heterogeneous microstructure was composed of the BCC α-Fe and FCC ε-Cu phases. This grain size gradient and heterogeneous microstructure ensure that the samples possess high shear and tensile strength. The formation mechanisms of the grain-size gradients and heterogeneous microstructures of the samples were further discussed. The proposed strategy that functionally graded materials with grain size gradients and heterostructures can be fabricated by additive manufacturing may open up a new avenue for materials design.