Influence of filament orientation and fabrication variables on the properties of fiber-reinforced metals
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Continuous t u n g s t e n - f i l a m e n t , r e i n f o r c e d s i l v e r - m a t r i x c o m p o s i t e s w e r e p r e p a r e d by e l e c t r o p l a t i n g , c o l d p r e s s i n g , and hot p r e s s i n g techniques followed by s i n t e r i n g , in the r a n g e of 2 to 33 vol pct f i l a m e n t s . O r i e n t a t i o n of the f i l a m e n t s with r e s p e c t to the t e n s i l e a x i s was v a r i e d b e t w e e n 0 ( p a r a l l e l ) and 90 deg. The p r o p e r t i e s d e t e r m i n e d w e r e the u l t i m a t e t e n s i l e s t r e n g t h , 0.1 pct y i e l d s t r e n g t h , p r o p o r t i o n a l l i m i t , e l o n g a t i o n , and e l a s t i c modulus. The r e s u l t s i n d i c a t e that the s t r e n g t h e s s e n t i a l l y followed the r u l e of m i x t u r e s . A m i s a l i g n m e n t e x c e e d i n g 10 to 15 d e g d r a s t i c a l l y r e d u c e s s t r e n g t h . A s m a l l m i s a l i g n m e n t of l e s s than 10 deg not only d o e s not lower the s t r e n g t h but g r e a t l y i m p r o v e s the d u c t i l i t y . F i v e d i f f e r e n t f r a c t u r e p a t h s w e r e i d e n t i f i e d a s a function of f i b e r o r i e n t a t i o n . Both d u c t i l e and b r i t t l e f r a c t u r e w e r e o b s e r v e d in the t u n g s t e n f i l a m e n t s . Many of the f e a t u r e s of d e f o r m a t i o n and f r a c t u r e w e r e c h a r a c t e r i z e d b y Scanning E l e c t r o n M i c r o s c o p y . / H E b a s i c o b j e c t i v e of t h i s p r o g r a m was to s t u d y the influence of d i f f e r e n t p r o c e s s i n g t e c h n i q u e s on the p r o p e r t i e s of f i b e r - r e i n f o r c e d m e t a l s . The e f f e c t of p r o c e s s i n g p a r a m e t e r s and f i l a m e n t o r i e n t a t i o n on the m e c h a n i c a l p r o p e r t i e s and f r a c t u r e m o d e s of s i l v e r matrix-tungsten filament composites was investigated. P a r t i c u l a r e m p h a s i s was p l a c e d on the o r i e n t a t i o n e f f e c t of continuously a l i g n e d f i b e r s on s t r e n g t h , d e f o r m a t i o n , and f r a c t u r e b e h a v i o r of t h e s e c o m p o s i t e s . Since the a b i l i t y of the f i l a m e n t and the m a t r i x to s h a r e the load d e t e r m i n e s the u l t i m a t e b e h a v i o r of the c o m p o s i t e , it i s only l o g i c a l that the f a b r i c a t i o n p a r a m e t e r s take on a d d e d i m p o r t a n c e in t h e s e s y n t h e t i c s t r u c t u r e s . The l o a d t r a n s f e r c a p a b i l i t i e s a r e d e t e r m i n e d not only by the f i l a m e n t p r o p e r t i e s but a l s o by the m a t r i x c h a r a c t e r i s t i c s and the i n t e r f a c e . The d u c t i l i t y would a l s o be g o v e r n e d by the s a m e p a r a m e t e r s . T h u s , the m e t h o d of m a k i n g the c o m p o s i t e s - w h e t h e r by s i n t e r i n g , i n f i l t r a t i o n , e l e c t r o d e p o s i t i o n , hot w o r k i n
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