a method of manufacturing a heterogeneous composite includes the steps of providing a first constituent and a second constituent , wherein the first constituent is porous or capable of developing pores when under hydrostatic pressure , and the second constituent comprises a solid having thermoplastic properties ; positioning the second constituent relative to the first constituent and coupling energy into the second constituent to cause at least portions of the second constituent to liquefy and to penetrate into pores or other structures of the first constituent , whereby the first constituent is interpenetrated by the second constituent to yield a composite ; and , causing an irreversible transition at least of the second constituent to yield a modified composite .