137-140, 1989. Pergamon Press plc. Printed in the U.S.A. ... (I"i") Dept. of Materials Science and Engineering, Stanford University,. Stanford, CA 94305, USA.
Scripta METALLURGICA
Vol. 23, pp. 137-140, 1989 Printed in the U.S.A.
Pergamon
Press plc
M E C H A N I C A L P R O P E R T I E S OF P A R T I C U L A T E C O M P O S I T E S B A S E D ON A B O D Y - C E N T E R E D - C U B I C M g - L i ALLOY C O N T A I N I N G BORON R.T. Whalen(*), G. Gonz~tlez-Doncel (**) , S . L . R o b i n s o n ( t ) a n d O.D. S h e r b y ( t t ) (*) N A S A - A m e s Research Center, Moffett F i e l d , CA 94035, U S A (**) Centro N a t i o n a l de I n v e s t i g a c i o n e s Metahirgicas (C. S. I . C ) , Av. de G r e g o r i o del Amo 8, 28040 M a d r i d , Spain ( t ) S a n d i a N a t i o n a l L a b o r a t o r i e s , L i v e r m o r e , CA 94555, U S A (I"i") Dept. of Materials Science and E n g i n e e r i n g , S t a n f o r d U n i v e r s i t y , S t a n f o r d , C A 94305, U S A ( R e c e i v e d O c t o b e r 6, 1988) ( R e v i s e d O c t o b e r 26, 1988) IaLrmlacLion H u s e b y e t al ( I ) s h o w e d that a high specific s t i f f n e s s of 4.3x106 m could be achieved in m a g n e s i u m by the adition o f 25 volume percent o f b o r o n particles. P o o r tensile ductility p r o p e r t i e s were o b t a i n e d , h o w e v e r , which were attributed to the large volume fraction o f hard particles and to the low ductility o f the hop m a g n e s i u m matrix. The p u r p o s e of the present i n v e s t i g a t i o n was to i m p r o v e the ductility o f Mg-B c o m p o s i t e s by substituting for magnesium a Mg-14wt%Li s o l i d s o l u t i o n alloy. Such an alloy is k n o w n to e x h i b i t high ductility because of its b o d y - c e n t e r e d - c u b i c structure (2). Another a d v a n t a g e o f adding lithium is that it decreases the density o f m a g n e s i u m (3), and therefore the specific s t i f f n e s s can be expected to increase. Material s,_P r oc e s ~ d n g _ a a d . ~ e , rimenlal.l?r~r,.~dur e The m a g n e s i u m - l i t h i u m alloy was the c o m m e r c i a l alloy LA-141 (14.1wt% Li and 1.5wt% A1) s u p p l i e d by Mr. E. W i l l n e r o f the L o c k h e e d M i s s i l e s and Space C o r p o r a t i o n , Sunnyvale, California. The a s - r e c e i v e d bar was machined into c h i p s , in a dry argon atmosphere, in sizes less than 25gm. B o r o n , as -200 mesh (
