A survey of the effects of ternary and quaternary alloying on the stability and properties of uranium-zirconium, -- niobium, and -- molybdenum-base gammaphase alloys was conducted. The effects of ternary and quaternary additions of chromium, molybdenum, niobium, ruthenium, vanndium, and zirconium on transformation kinetics, transformation temperature, hot hardness, and corrosion resistance were investigated. Niobium or molybdenum additions to uranium-- zirconium-base alloys increased thermal stability and hot hardness of the gamma phase and lowered transformation temperatures. Those additions also generalty resulted in improved corrosion resistance. Zirconium increased the gamma-phase stability in uranium-niobium-base alloys, lowered transformation temperatures, and in some amounts increased hot hardness and improved corrosion resistance. Variable corrosion behavior of the uranium--niobium-- zirconium alloys is probably attributable to lack of homogeneity. Molybenum additions had either a negligible or detrimental effect on the thermal stability of the uranium-- niobium gamma phase, although molybdenum did lower the temperature at which alpha uranium begins to decompose on heating. The addition of 1 wt. % molybdenum to the 10 wt. % niobium alloy or 3 wt. % molybdenum to the 20 wt. % niobium alloy resulted in maximum hardness of the gamma phase at elevated temperatures, the hot hardness decreasing with larger aditions. Generally little effect of molybdenum on the corrosion resistance of uranium- niobium-base alloys was noted, although a 3 wt. % addition was found to increase the corrosion life of the 10 wt.% niobium alloy. Niobium additions of up to 3 wt.% to the 7.5 wt. % molybdenum-base alloy and of 1 wt. % to the 10 and 12 wt. % molybdenum-base alloy; increase the thermal stability of the gamma phase; larger niobium additions decreased stability. A possible slight increase in the temperature of gamma formation on heating accompanied the addition of niobium. Ruthenium increased gamma stability more effectively, while it depressed the temperature of transformation to gamma. However, ruthenium decreased the hot hardness of the uranium--molybdenum gamma phase both as a ternary addition and as a quaternary addition to uranium-- molybdenum-- niobium alloys. Niobium additions to the 7.5 wt. % molybdenum alloy increased hot hardness, while additions above 1 wt. % to the 10 and 12 wt. % molybdenum alloys decreased hot hardness. Ruthenium and niobium additions both increased the corrosion resisthnce of uranium-- molybdenum alloys. Zirconium additions were found to be generally detrimental to thermal stability, hot hardness, and corrosion resistance of the uranium-- molybdenum gamma phase, while vanadium and chromium additions exhibited a negligible effect. (auth).