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The rare earths thulium, lutetium, and yttrium were added t o uranium and uranium alloys in the range of 0.1-0.3 wt 9. Nickel, cobalt, and rhodium were used as carrier metsls for the rare earths. lhese carrier metals are partially soluble in uranium and also exhibit part ial solubility for the rare earths. The room temperature tensile strength, yield strength, elongation, calculated modulus, and hardness wen obtained fo'r both asrolled and vacuum-annealed sheet stock. Grain size, hardness, and density values were obtained on the as-cast alloys for comparison. A developoent program was undertaken a t the U s Alamos Scientific Laboratory (LASL) to d e t e d n e the effect of rare-earth elements on the mechanicsl and physical properties of uranium and uranium alloys. The f i r s t samples were made by including the rare earths with the uranium a t the tims the crucible was loaded. However, or& about 50-500 ppu of rare earths wtam sletained in the melt . Further invsstigations indicated that three characteristics of the rare earths introduced problems i n alloying with uranium. The f i r s t problem was created by the dens i ty extremes between uranium (lr8.93 d o c ) and the rare earths thulium (9.33 g/cc), l u t e t i u m (9.84 g/cc), and y t t r i u m (4.47 g/cc 1. The second ~aroblem w that the high vapor pressure of some of the rare J ' .%: eastha a t the malting point of uranium (l130°c) rea ; y r : sulted in losses during vacutrm melting. A third 72 LqiL, . 0 problem was that of the limited solubility of the rare earths in uranium, as reportcd by Raefling and Dame.' Their mrk indicated a maximum solubility of 0.04 w t 9 thulium at 122!j0c, 0.40 wt 46 lutetium a t 1200Oc, and 0.14 w t $ y t t r i u m a t la2gWc. The density variation causes the lower-density rare earths either to f loat t o the top of the casting or to remain in the crucible residue. A aeries of experiments shared that segregation of the rare earths could be overcome when the rare earths were added with a carrier metal that was soluble in mlten uranium. lhis rare earth-carrier metal button was introduced into the uranium melt a few minutes prior ta induction st i rr ing and pouring. Ch i l l casting prevented liquation of the rare earths during solidification of the me l t . This report describes the alloying and casting procedures developed a t the h s AleJPos Scientific Iaborafory for producing lmmgencous uranium and uranium allays contsMng 0.1-0.3 wt $ of the rare earths thulium, lutetium, and yttrium. Some physical property data were also obtained as a part of the program. The furnace used to melt and cast the uraniumrare earth alloys is shown in Figs. 1 and 2. The l i d of the f'uznace contained a sight glass through which metel temperatures could be determined by an wzica2 l?ammwbr. !@he %sil?gM1 mpp* d w rogs located auch that Che flow of s r g o ~ ~ t e d foe* * Q ~ ~ ~ ~ ~ B . ThelMwwhc3dbplaceby made from a mgltite apodwptely 2 h. diam r 4 in. lone, wZth a M h D h b i l l e d per~~ to ita a;rds. All Obs graph$* n\riacer were coated with WDld Wash A te prevent carbon pbhup bp the uranlm Wt. A Q.OBie-rin.-thfLek piece of a ~ ~ ~ % m p foil mes mzppTted by gram*. rbga at each end of the diqienea~ oavl,tyty w?&h aon8aincd tha raser eart;& &&Utiopls. 'Eltb iltspaaaer var. rated orrta the mvable tungsben rod and heJa abow the eurfa~~ 0f WSl%m ~$il CPl(r hU-F%g, 4 8t;esE I @E vacuum a+/or mepa stmomere krdffctian stimislg of the c wm b.gun. At thls -e. 2. S o ~ t i o 6evr of all metal induction type vacuum and/or argon cltmoq,bm m e . time the dispenser was la~?red into the mslt and the TABLE I m e t a l was added to the molten uranium by melting of CHWICAL ANALYSIS OF RAW MA-

ADDITION OF RARE EARTHS TO URANIUM AND URANIUM ALLOYS.