Which of the following composite examples are expected to have isotropic properties? Select as many as appropriate.
1) 6061 polycrystalline aluminum with randomly oriented grains, reinforced with unidirectional silicon carbide fibers
2) soda glass reinforced with random 3D steel wires
3) an amorphous elastomer (polymer) reinforced with a random distribution of carbon particles.
4) an Al-Cu alloy consisting of a single crystal of alpha phase reinforced with a random distribution of theta precipitates (The Al-Cu phase diagram is shown in Fig. 11.24, Callister 7e).