Composite structures having a higher density, stronger reinforcing niobium based alloy embedded within a lower density, lower strength niobium based cladding alloy are provided. The cladding is preferably an alloy having a niobium and titanium base according to the expression:Nb.sub.balance -Ti.sub.31-48 -Al.sub.8-21.The reinforcement may be in the form of plates, sheets or rods of the higher strength, higher temperature niobium based reinforcing alloy. The same crystal form is present in both the matrix and the reinforcement and is specifically body centered cubic crystal form.