The physical and welding metallurgy of Gd-enriched austenitic alloys has been investigated. Type 316L stainless steel alloys with up to 6 wt% Gd were observed to solidify in the primary ferrite mode and terminate solidification by a peritectic reaction involving a (Fe,Ni,Cr)3Gd. Essentially no Gd is dissolved in either the ferrite or austenite phases. Heating of the as-cast alloys leads to liquation of the (Fe,Ni,Cr)3Gd intermetallic at approx. 1060 oC. As a result, the solidification temperature range of these alloys is very large (360°C to 400°C). The large solidification temperature range leads poor hot ductility and weldability, and limits production of Gd enriched stainless steels on a commercial basis. Subsequent work demonstrated that this difficulty can be surmounted by the addition of Gd to nickel base alloys. Three different nickel alloy matrix compositions were chosen that were similar to commercial Ni-Cr-Mo base alloys. The Gd level of each alloy was approx. 2 wt%. All the alloys initiated solidification by formation of primary austenite and terminated solidification by a eutectic-type reaction at ~1270°C involving austenite and Ni5Gd. The solidification temperature range of the alloys varied from approx. 100 to 130°C (depending on alloy composition). This is a substantial reduction compared to the solidification temperature range of Gd-enriched stainless steels. The higher temperature eutectic reaction that occurs in the nickel base alloys is accompanied by significant improvements in hot ductility and solidification cracking resistance. The results of this research demonstrate that Gd-enriched nickel base alloys are excellent candidate materials for nuclear criticality control in spent nuclear fuel storage applications that require production and fabrication of large amounts of material through conventional ingot metallurgy and fusion welding techniques.