Can a solid defuse into both a liquid and a solid

Diffusion of one state of matter into another: Solid can diffuse in liquid. When sugar is added to water, whole water becomes sweet without stirring it because of diffusion of sugar into water. ... Carbon dioxide and oxygen are the two gases in air which dissolves in water by diffusion.

Well solid can difuse to a liquid by add ingredients heat or melting something and liquid can go back to solid by freezing or letting something cool i don’t really know but if your asking if solid can difuse solid Yes it is possible that, the solid diffuses into solid . If we write on the blackboard and leave it uncleaned for a longer time we will observe that it is difficult to clean the blackboard afterwards. This is because of the diffusion of chalk particles into the blackboard also that part i looked up but makes sense