Room temperature creep of borsic-aluminum composites
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E P in metal m a t r i x c o m p o s i t e s has g e n e r a l l y been investigated at elevated t e m p e r a t u r e s . 1-16 At room t e m p e r a t u r e Wilcox and "Clauer 17 o b s e r v e d that the s t r a i n , E, v a r i e d l i n e a r l y with the l o g a r i t h m of time ( l o g a r i t h mic c r e e p ) in a unidirectional s t a i n l e s s s t e e l - m a g n e sium alloy composite. They concluded that composite c r e e p was controlled by c r e e p of the f i l a m e n t s . Pinnel and Lawley ~ a l s o concluded that room t e m p e r a t u r e c r e e p in a s t a i n l e s s s t e e l - a l u m i n u m composite was cont r o l l e d by c r e e p of the f i l a m e n t s although in this s y s t e m s t e a d y - s t a t e c r e e p was o b s e r v e d . Antony and Chang 2 detected c r e e p in a unidirectional B-A1 composite in the t e m p e r a t u r e range 121 ~ to 316~ and suggested that composite c r e e p is governed by d e f o r m a t i o n of the B f i l a m e n t s . Toth 6 o b s e r v e d c r e e p in unidirectional and c r o s s p l i e d B-A1 c o m p o s i t e s at 204 ~ and 316~ Three s t a g e s of c r e e p were o b s e r v e d in the 0 deg c o m p o s i t e s : 1) s t r a i n on loading, 2) a q u a s i f i r s t stage where e l a s t i c s t r a i n i n g of the f i l a m e n t s takes place as the m a t r i x r e l a x e s , and 3) a second stage thought to be c o n t r o l l e d by c r e e p of the filaments. In the :L 45 deg c r o s s p l i e d o r i e n t a t i o n s extensive p r i m a r y c r e e p was o b s e r v e d and the f i l a m e n t s were r o t a t e d as much as 24 deg. Sheerer and C h r i s t i a n ~4 o b s e r v e d c r e e p in unidirectional and 0 + 90 deg B-A1 c o m p o s i t e s at 371~ Creep and s t r e s s - r u p t u r e of Borsic-A1 was investigated by Breinan and K r e i d e r ~8 at t e m p e r a t u r e s between 300 ~ and 600~ Little p l a s t i c deformation was r e p o r t e d ; however, their s t r a i n m e a s u r i n g s e n s i t i v i t y was limited. The p r e s e n t study was initiated to d e t e r m i n e if c r e e p and time dependent f a i l u r e could be o b s e r v e d in B o r s i c A1 c o m p o s i t e s at room t e m p e r a t u r e . The c r e e p behavi o r of B o r s i c f i l a m e n t s and unreinforced m a t r i x m a t e r i a l was also investigated for c o m p a r i s o n with the c o m posite c r e e p r e s u l t s .
PROCEDURE Composite F a b r i c a t i o n Borsic-A1 c o m p o s i t e s were f a b r i c a t e d by the diffusion bonding of m o n o l a y e r tapes. The tapes were p r e p a r e d by winding 4.3 rail (0.11 ram) B o r s i c f i l a m e n t s on a c y l i n d r i c a l m a n d r e l which was then p l a s m a s p r a y e d with 1100 A1. The tapes were then s t a c k e d in l a y e r s to produce balanced and s y m m e t r i c c o m p o s ite p l a t e s having f i l a m e n t s o r i e n t e d 0, 90, • 45, 0 + 60, and 0 + 90 deg with r e s p e c t to the long d i r e c t i o n of the plate. The hot p r e s s i
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