We report the synthesis of nanocomposites of Bi in an aluminum based metallic glass matrix by rapid solidification. It is shown that constrained melting and solidification of nanometer sized embedded Bi particles lead to the formation of symmetry related multidomained particles. The Bi particles exhibit a significantly large depression of bulk melting point (over 100 K) requiring a free energy gain of greater than 0.7×108J m−3. This cannot be explained by the size dependence of melting points or other pressure effects and represents an intrinsic characteristic of the multidomained particles. ©1996 American Institute of Physics.