The disclosure describes example techniques and assemblies for joining a first component and a second component. The techniques may include positioning the first and second component adjacent to each other to define a joint region between adjacent portions of the first component and the second component. The techniques may also include inserting a solid retainer material into the joint region through an aperture in one of the first component or the second component to form a mechanical interlock between the first component and the second component and sealing the aperture to retain the solid retainer material within the joint region. The solid retainer material includes at least one of a metal, a metal alloy, or a ceramic.