Another commonly employed space-holder for titanium foams is urea, which yielded porosities from 20 to 75%. Wen et al. produced foams exhibiting a bimodal pore distribution with porosities ranging from 55 to 75%, Young's moduli between 3–6.4 GPa, and a plateau stress of 10–35 MPa. An inverse relationship between plateau stress and porosity was observed with increased porosity resulting in decreased plateau stress. Tuncer et al. utilized urea in combination with irregularly shaped titanium powders in an effort to increase green strength through increased packing efficiency (of particles). This also eliminated the need for the incorporation of a binder.