Disclosed are processes and compositions for fabricating irradiation targets from slurry compositions using a slip casting method to form a layer of the slurry composition on a substrate. The layer of slurry is allowed to dry on the substrate to produce a green cast layer that may then be cut, milled or otherwise machined to form intermediate targets having one or more predetermined configurations. These intermediate targets are subsequently subjected to a thermal process by which organic components remaining in the green cast layer are driven off and/or oxidized to form a densified, substantially inorganic, layer that has a density below that of the primary particles.