It kind of is, but it happens within the molten part, so it's harder to control (and, considering how hard, I'd say the science behind it is still poorly understood).
They get perfect enough single crystal superalloy blades every time ... after throwing out the half that fail. The science is well understood, even if it's fiendishly hard [0]
0 - https://www.asme.org/wwwasmeorg/media/resourcefiles/aboutasm...