New liberation model was created considering preferential breakage at phase boundaries of solid materials for evaluating facility with disassembly and solid/solid separation in the area of material recycling. Two kinds of models have been developed in the paper, one is a prototype and simplest model and the other one involves the concept of strength distribution at phase boundary. These models include the modification of the Wiegel model, one of the most popular and acceptable liberation models, as well as the definition of "preferential breakage probability" at phase boundary. The indices could become good measures to evaluate the product design and to describe suitability of disassembly and/or compositional separation for material recycling. Concept, structure, simulation results, and validation of these models are shown in the paper.