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Solid solution formation in the barium titanate-zirconate system
Dept.,, Tokyo, J a p a n . ) J. Japn Soc. Powder and Powder Metallurgy, Vol 38, No 5, 1991, 581-585. (In Japanese.) It is r e p o r t e d t h a t t h e a d d i t i o n of Re refines t h e microstructure, increases t h e s t r e n g t h a n d reduced tile ductility of W-FeNi heavy alloys. The changes resulting from t h e Re a d d i t i o n s a r e d i s c u s s e d w i t h r e f e r e n c e to m i c r o s t r u c t u r e , size of f r a c t u r e s o u r c e a n d t o u g h n e s s of t h e matrix.
Proszkow, Vol 24, no 3, 1991, 87-92. (In Polish.) The p a p e r p r e s e n t s a discussion of t h e g r a n u l a t i o n of powders which are difficult to c o m p a c t such as W. Available m e t h o d s are reviewed. REMOVAL O F NICKEL ACTIVATOR FROM S I N T E R E D T U N G S T E N COMPACTS BY VACUUM T R E A T M E N T L.H.Moon et al.
GOLD AND PLATINUM COATED T U N G S T E N WIRE FOR USE AS DISCHARGE T U B E E L E C T R O D E S K.Hara, N.Goto.
( N i p p o n T u n g s t e n Co.,
Fukuoka, J a p a n ) Nippon Tungsten Rev/ew, Vol 23, 1990, 36-40. The d e v e l o p m e n t of d o p e d W wire, coated with 0.2~tm Au a n d 1.5lamPt, w h i c h w e r e a p p l i e d by e l e c t r o d e p o s i t i o n is described. The function of t h e Au is to prevent t h e formation of brittle p h a s e s between W a n d Pt by acting as a b a r r i e r to diffusion. The d o u b l e c o a t e d w i t h was s u b j e c t e d to w i r e d r a w i n g a n d g o o d a d h e s i o n is r e p o r t e d w h e n t h e doped wire was free from porosity. The durability of t h e clad wire was assessed in t h e discharge tube of a photo-copying m a c h i n e a n d was reported to be satisfactory. T E N S I L E BEHAVIOUR O F D O P E D T U N G S T E N WIRE AT H I G H TEMPERATURES I~Fujii et al. (Nippon T u n g s t e n Co., Fukuoka, Japan) Nippon Tungsten Review, Vol 23, 1990, 41-50. The tensile p r o p e r t i e s of d o p e d W wire were assessed at 2200 a n d 2400°C, in H or N, with reference to t h e grain size of t h e wire. It is r e p o r t e d t h a t w h e n t h e grain size is large d e f o r m a t i o n is t r a n s g r a n u l a r a n d t h a t grain b o u n d a r y sliding occurs w h e n t h e grain size is small. Fracture m o d e s in H wree ductile or m e l t i n g a n d in N t h e fractures were i n t e r g r a n u l a r or brittle t h e difference being a t t r i b u t e d to t h e p r e s e n c e of O. RARE EARTH D O P E D T U N G S T E N LAMP E L E C T R O D E MATERIALS Y.Tagawa et al, ( N i p p o n t u n g s t e n Co., Fukuoka, Japan) Nippon Tungsten Rev/ew, Vol 23, 1990, 51-58. A study is r e p o r t e d of t h e use of rare e a r t h oxides, i n s t e a d of Th02, in non-sag W wire with t h e object of improving l a m p p e r f o r m a n c e a n d a v o i d i n g t h e use of radioactive material. Oxides of Gd a n d pr, u s e d a s d o p a n t s w e r e s a i d t o give satisfactory results. GRANULATION O F D I F F I C U L T TO COMPACT POWDERS SUCH AS TUNGSTEN A.Moszcynski et al. (Wojskowa A c a d e m i a Techniczna, Warsaw, Poland.) Metalurgia
( H a n Yang University,
Seoul, Korea.) J. Less Common Metals, Vol 170, No 1, 1991, 15-25. The p o s s i b i l i t y of r e m o v i n g t h e Ni activator fromsintered W compacts c o n t a i n i n g 0.2 o r 0.4wt%Ni b y h e a t t r e a t m e n t at 1400°C in high v a c u u m was investigated. It is r e p o r t e d t h a t u n d e r o p t i m u m conditions t h e Ni c o n t e n t could be reduced to 0.07% w h i c h is equivalent to t h e solubility of Ni in W. The removal of t h e Ni is said to m i n i m i s e t h e risk of t h e W being embrittled. Porosity and pore morphology were found to influence t h e removal of t h e Ni.
M I C R O S T R U C T U R E AND P R O P E R T I E S O F T U N G S T E N - N I C K E L - C O P P E R HEAVY ALLOYS J.Li, J.Huang. (Central S o u t h University of Technology, China.) Rare Metals (China), Vol 9, No 4, 1990, 287-291.. (In Chinese.) S t r u c t u r e / p r o p e r t y r e l a t i o n s h i p s in WNi-Cu heavy alloys have been studied using electron p r o b e microanalysis. The causes of i n h o m o g e n e i t y , low f r a c t u r e s t r e s s a n d f r a c t u r e m e c h a n i s m s in t h e alloy a r e discussed,
T U N G S T E N - R H E N I U M ALLOY W I R E S J.Cai et al, ( S h a n g h a i I r o n a n d Steel r e s e a r c h Ins., S h a n g h a i , C h i n a . ) Wire Industry, Vol 58, No 3, 1991, 133-134. An outline of problems, including in h o m o g e n e i t i t e s of composition, b u b b l i n g effects d u r i n g s i n t e r i n g a n d b r e a k s in winding, e n c o u n t e r e d in t h e p r o d u c t i o n of W-Re alloys wires is presented. The p a p e r summarises laboratory and commercial e x p e r i e n c e in t h e p r o c e s s i n g of W(1.3.15,20,26 a n d 28)wt%Rewires.
E X P E R I M E N T A L INVESTIGATIONS INTO T H E COLD C O M P A C T I N G O F T U N G S T E N BARS FROM POWDERS S.A.Mymrin et al. Kuznechno-Shtampov., No 9, 1990, 15-18. (In Russian.) The cold c o m p a c t i n g of long W bars was investigated industrially w i t h respect to bulk density of t h e powers, compacting p r e s s u r e a n d t h e density of t h e c o m p a c t e d bars. The results were analysed statistically a n d n o m o g r a m s for industrial compacting are presented,
ZINC .................................................................. OXIDE AND CARBIDE R E I N F O R C E D S U P E R P L A S T I C ZINC-ALUMINIUM BASED ALLOY C O M P O S I T E S K.Okimoto et al. ( G o v e r n m e n t Industrial Research Ins., Kyushu, J a p a n . ) J.Japan Soc, Powder and Powder Metallurgy, Vol 38, No 5, 1991, 668-672. (In Japanese.) An Al-22%Zn alloy powder was mixed w i t h Ko_6Ti02, A120a, Zr02 or SiC a n d processed into compacts which are characterised with respect to t h e effects of process p a r a m e t e r s on t h e densification a n d properties. It was r e p o r t e d t h a t t h e alloy w i t h 15% A1203 was superplastic forming.
AND MA'~R~A~-S
ELECTRICAL MAGNETIC .
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A M O R P H I Z A T I O N O F SOFT M A G N E T I C ALLOYS B Y M E C H A N I C A L A L L O Y I N G (MA) S.Surinach et ai. (Universitat A u t o n o m a de Barcelona, Barcelona, Spain.) Materials Science and Engineering A, Vol A134, 1991, 1368-1371. MA Fe-20at%B a n d Fe-15%B-10%Si alloy powders were e x a m i n e d by X-ray diffraction a n d differential s c a n n i n g calorimetry. In a d d i t i o n to a well e s t a b l i s h e d e x o t h e r m i c effect a n e n d o t h e r m i c effect was found after 300 h o u r s milling. The activation energy a n d e n t h a i p y of this were d e t e r m i n e d a n d correlated with t h o s e for recrystallisation. SOLID SOLUTION FORMATION IN T H E BARIUM TITANATE-ZIRCONATE SYSTEM D.Kolar et al, (University of Ljubljana, Yugoslavia.) Science of Sintering, Vol 23, No 3, 1991, 143-150. The factors which determine the formation, during sintering, of Ba t i t a n a t e / Ba zirconate solid solutions are discussed. The m e c h a n i s m is said to be diffusion of Ti ions a n d is a c c o m p a n i e d by a volume e x p a n s i o n . K i n e t i c s of s o l i d s o l u t i o n formation are r e p o r t e d to be influenced by particle size a n d size distribution. FABRICATION O F A M A G N E T I C C O M P O S I T E MATERIAL F R O M S U P E R P L A S T I C ZINC-ALUMINIUM ALLOY POWDER I~Okimoto et ai. ( G o v e r n m e n t Industrial Research Ins., Kyushu, J a p a n . ) J. Japan Soc, Powder and Powder Metallurgy, Vol 38, No 5, 1991, 673-680. (In Japanese.) T h e p r o d u c t i o n of a s u p e r p l a s t i c m a g n e t i c alloy by b l e n d i n g Zn-22%A1 powder with a m a g n e t i c p r o p e r t i e s by t h e d e t e r m i n a t i o n of o p t i m u m p r o c e s s i n g
MPR April 1992 51
Proszkow, Vol 24, no 3, 1991, 87-92. (In Polish.) The p a p e r p r e s e n t s a discussion of t h e g r a n u l a t i o n of powders which are difficult to c o m p a c t such as W. Available m e t h o d s are reviewed. REMOVAL O F NICKEL ACTIVATOR FROM S I N T E R E D T U N G S T E N COMPACTS BY VACUUM T R E A T M E N T L.H.Moon et al.
GOLD AND PLATINUM COATED T U N G S T E N WIRE FOR USE AS DISCHARGE T U B E E L E C T R O D E S K.Hara, N.Goto.
( N i p p o n T u n g s t e n Co.,
Fukuoka, J a p a n ) Nippon Tungsten Rev/ew, Vol 23, 1990, 36-40. The d e v e l o p m e n t of d o p e d W wire, coated with 0.2~tm Au a n d 1.5lamPt, w h i c h w e r e a p p l i e d by e l e c t r o d e p o s i t i o n is described. The function of t h e Au is to prevent t h e formation of brittle p h a s e s between W a n d Pt by acting as a b a r r i e r to diffusion. The d o u b l e c o a t e d w i t h was s u b j e c t e d to w i r e d r a w i n g a n d g o o d a d h e s i o n is r e p o r t e d w h e n t h e doped wire was free from porosity. The durability of t h e clad wire was assessed in t h e discharge tube of a photo-copying m a c h i n e a n d was reported to be satisfactory. T E N S I L E BEHAVIOUR O F D O P E D T U N G S T E N WIRE AT H I G H TEMPERATURES I~Fujii et al. (Nippon T u n g s t e n Co., Fukuoka, Japan) Nippon Tungsten Review, Vol 23, 1990, 41-50. The tensile p r o p e r t i e s of d o p e d W wire were assessed at 2200 a n d 2400°C, in H or N, with reference to t h e grain size of t h e wire. It is r e p o r t e d t h a t w h e n t h e grain size is large d e f o r m a t i o n is t r a n s g r a n u l a r a n d t h a t grain b o u n d a r y sliding occurs w h e n t h e grain size is small. Fracture m o d e s in H wree ductile or m e l t i n g a n d in N t h e fractures were i n t e r g r a n u l a r or brittle t h e difference being a t t r i b u t e d to t h e p r e s e n c e of O. RARE EARTH D O P E D T U N G S T E N LAMP E L E C T R O D E MATERIALS Y.Tagawa et al, ( N i p p o n t u n g s t e n Co., Fukuoka, Japan) Nippon Tungsten Rev/ew, Vol 23, 1990, 51-58. A study is r e p o r t e d of t h e use of rare e a r t h oxides, i n s t e a d of Th02, in non-sag W wire with t h e object of improving l a m p p e r f o r m a n c e a n d a v o i d i n g t h e use of radioactive material. Oxides of Gd a n d pr, u s e d a s d o p a n t s w e r e s a i d t o give satisfactory results. GRANULATION O F D I F F I C U L T TO COMPACT POWDERS SUCH AS TUNGSTEN A.Moszcynski et al. (Wojskowa A c a d e m i a Techniczna, Warsaw, Poland.) Metalurgia
( H a n Yang University,
Seoul, Korea.) J. Less Common Metals, Vol 170, No 1, 1991, 15-25. The p o s s i b i l i t y of r e m o v i n g t h e Ni activator fromsintered W compacts c o n t a i n i n g 0.2 o r 0.4wt%Ni b y h e a t t r e a t m e n t at 1400°C in high v a c u u m was investigated. It is r e p o r t e d t h a t u n d e r o p t i m u m conditions t h e Ni c o n t e n t could be reduced to 0.07% w h i c h is equivalent to t h e solubility of Ni in W. The removal of t h e Ni is said to m i n i m i s e t h e risk of t h e W being embrittled. Porosity and pore morphology were found to influence t h e removal of t h e Ni.
M I C R O S T R U C T U R E AND P R O P E R T I E S O F T U N G S T E N - N I C K E L - C O P P E R HEAVY ALLOYS J.Li, J.Huang. (Central S o u t h University of Technology, China.) Rare Metals (China), Vol 9, No 4, 1990, 287-291.. (In Chinese.) S t r u c t u r e / p r o p e r t y r e l a t i o n s h i p s in WNi-Cu heavy alloys have been studied using electron p r o b e microanalysis. The causes of i n h o m o g e n e i t y , low f r a c t u r e s t r e s s a n d f r a c t u r e m e c h a n i s m s in t h e alloy a r e discussed,
T U N G S T E N - R H E N I U M ALLOY W I R E S J.Cai et al, ( S h a n g h a i I r o n a n d Steel r e s e a r c h Ins., S h a n g h a i , C h i n a . ) Wire Industry, Vol 58, No 3, 1991, 133-134. An outline of problems, including in h o m o g e n e i t i t e s of composition, b u b b l i n g effects d u r i n g s i n t e r i n g a n d b r e a k s in winding, e n c o u n t e r e d in t h e p r o d u c t i o n of W-Re alloys wires is presented. The p a p e r summarises laboratory and commercial e x p e r i e n c e in t h e p r o c e s s i n g of W(1.3.15,20,26 a n d 28)wt%Rewires.
E X P E R I M E N T A L INVESTIGATIONS INTO T H E COLD C O M P A C T I N G O F T U N G S T E N BARS FROM POWDERS S.A.Mymrin et al. Kuznechno-Shtampov., No 9, 1990, 15-18. (In Russian.) The cold c o m p a c t i n g of long W bars was investigated industrially w i t h respect to bulk density of t h e powers, compacting p r e s s u r e a n d t h e density of t h e c o m p a c t e d bars. The results were analysed statistically a n d n o m o g r a m s for industrial compacting are presented,
ZINC .................................................................. OXIDE AND CARBIDE R E I N F O R C E D S U P E R P L A S T I C ZINC-ALUMINIUM BASED ALLOY C O M P O S I T E S K.Okimoto et al. ( G o v e r n m e n t Industrial Research Ins., Kyushu, J a p a n . ) J.Japan Soc, Powder and Powder Metallurgy, Vol 38, No 5, 1991, 668-672. (In Japanese.) An Al-22%Zn alloy powder was mixed w i t h Ko_6Ti02, A120a, Zr02 or SiC a n d processed into compacts which are characterised with respect to t h e effects of process p a r a m e t e r s on t h e densification a n d properties. It was r e p o r t e d t h a t t h e alloy w i t h 15% A1203 was superplastic forming.
AND MA'~R~A~-S
ELECTRICAL MAGNETIC .
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A M O R P H I Z A T I O N O F SOFT M A G N E T I C ALLOYS B Y M E C H A N I C A L A L L O Y I N G (MA) S.Surinach et ai. (Universitat A u t o n o m a de Barcelona, Barcelona, Spain.) Materials Science and Engineering A, Vol A134, 1991, 1368-1371. MA Fe-20at%B a n d Fe-15%B-10%Si alloy powders were e x a m i n e d by X-ray diffraction a n d differential s c a n n i n g calorimetry. In a d d i t i o n to a well e s t a b l i s h e d e x o t h e r m i c effect a n e n d o t h e r m i c effect was found after 300 h o u r s milling. The activation energy a n d e n t h a i p y of this were d e t e r m i n e d a n d correlated with t h o s e for recrystallisation. SOLID SOLUTION FORMATION IN T H E BARIUM TITANATE-ZIRCONATE SYSTEM D.Kolar et al, (University of Ljubljana, Yugoslavia.) Science of Sintering, Vol 23, No 3, 1991, 143-150. The factors which determine the formation, during sintering, of Ba t i t a n a t e / Ba zirconate solid solutions are discussed. The m e c h a n i s m is said to be diffusion of Ti ions a n d is a c c o m p a n i e d by a volume e x p a n s i o n . K i n e t i c s of s o l i d s o l u t i o n formation are r e p o r t e d to be influenced by particle size a n d size distribution. FABRICATION O F A M A G N E T I C C O M P O S I T E MATERIAL F R O M S U P E R P L A S T I C ZINC-ALUMINIUM ALLOY POWDER I~Okimoto et ai. ( G o v e r n m e n t Industrial Research Ins., Kyushu, J a p a n . ) J. Japan Soc, Powder and Powder Metallurgy, Vol 38, No 5, 1991, 673-680. (In Japanese.) T h e p r o d u c t i o n of a s u p e r p l a s t i c m a g n e t i c alloy by b l e n d i n g Zn-22%A1 powder with a m a g n e t i c p r o p e r t i e s by t h e d e t e r m i n a t i o n of o p t i m u m p r o c e s s i n g
MPR April 1992 51