Consider a spherical particle of material B contained in a spherical shell of material A. The thermal expansion coefficient of B is greater than that of A so that when the object is heated an internal strain develops in both materials.
My first assumption (which I would like critiqued) is that the heat capacity of the composite will be greater than the sum of the two heat capacities of the constituent parts if they were separated. My reasoning is that because a portion of the heat energy transferred to the composite will be stored as elastic strain energy, it will take more energy to raise the temperature by the same amount as if they were separated and hence the heat capacity is higher.
The composite is heated to a temperature where the stress that develops in the outer material is great enough to rupture it (assume that the only difference in energy before and after fracture is the energy necessary to create the two new fracture surfaces - just take this to be true) and when the material fractures it completely relaxes and loses the ability to store elastic energy.
Firstly, if we set the surface energy to zero, what happens to the elastic strain energy in the composite when it fractures? My thoughts are maybe some work is done on the environment but what if the composite is in a vacuum?
Secondly, if the two parts of the composite have become completely detatched from one another, the total heat capacity will revert to the sum of material A and material B (which is lower than the heat capacity of the composite). Does this process cause an internal energy or temperature change?
