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Effects of precipitates and oxide dispersoids on creep in nickel-chronium-tungsten alloys
PM
morphology of Fe 1.75%Ni-l.5%Cu-0.5%Mo steels with C is described. Fractures are used to show the heterogeneity of t h e steels a n d this is confirmed by selected area energy dispersive analysis which showed the segregation of t h e alloy elements. SHEAT ROLLING OF WATER ATOMIZED IRON-CHRONIUMALUMINIUM ALLOY POWDERS
I. O h n a k a et al (Osaka University, Suita, Osaka, J a p a n ) , J. Japan Inst. of Metals, Vol 57, No 9, 1993, 1083-1088. (In Japanese). Rapidly solidified Fe-30%Cr-5%Al alloy powders were s h e a t h rolled. As reduction i n c r e a s e d t h e o x i d e films on p a r t i c l e surfaces were f r a g m e n t e d a n d p a r t i c l e b o n d i n g improved. Effects of additions of Ce w e r e s t u d i e d . W i t h o u t Ce t e n s i l e s t r e n g t h increased linearly with reduction in the range 45 to 75%. With Ce t h e tensile s t r e n g t h was found to be low for small restrictions b u t at 60% s t r e n g t h s with a n d without Ce w e r e s i m i l a r . F r a c t u r e characteristics changed from i n t e r g r a n u l a r to t r a n s g r a n u l a r as deformation increased. CHEMICOTHERMAL PROCESSING OF IRON-BASE ALLOY POWDERS
A.P. Epik, M. A d a l l a k h , Poroshkovaya Metallurgiya, No 8, 1993, 37-43. (In Russian). Chromizing a n d boronizing of Fe base powders is described, t h e kinetics of growth of diffusion layers are shown to d e p e n d on diffusion saturation, alloy composition a n d porosity. Mechanical properties were determined. Wear properties are reported to b e e n h a n c e d by c h r o m i z i n g a n d b o r o n i z i n g w i t h o u t i n c r e a s e in o t h e r mechanical properties. Chromizing and b o r o n i z i n g are r e p o r t e d to t a k e 3 to 4 h o u r s at l l00°C a n d 2 to 3 h o u r s at l()00 ~C respectively.
Nickel E F F E C T S OF PRECIPITATES AND OXIDE D I S P E R S O I D S ON CREEP IN NICKEL-CHRONIUM-TUNGSTEN ALLOYS
S.l. Kwun, J.S. Cho (Korea University, Seoul, Korea), J. Korean Inst. of Metals. Vol 31, No 6, 1993, 757-765. (In Korean), High t e m p e r a t u r e tensile a n d creep tests were carried out on Ni-20%Cr-4%W which was s i n t e r e d from m e c h a n i c a l l y alloyed powders. The alloys contained y' precipitates a n d Y20:~ dispersoids. It is r e p o r t e d t h a t zone a n n e a l i n g i n c r e a s e s s t r e n g t h a n d c r e e p r e s i s t a n c e d u e to increased grain size a n d aspect ratio. Y203 acts as a dispersion s t r e n g t h e n i n g a g e n t a n d improves t h e r m a l stability of t h e y' precipitates at high temperatures. Up to
LITERATURE
REVIEW
950"C t h e ¥' precipitates c o n t r i b u t e d more to high t e m p e r a t u r e properties. The Y203 is considered to c o n t r i b u t e more to creep resistance t h a n tensile strength.
Titanium PRODUCTION OF TITANIUM BORIDE POWDERS FROM WASTE MATERIALS
I.V. Sokol et al, Poroshkovaya Metallurgiya, No 8, 1993, 1-7. (In Russian). The possibility of making TiB2 from Ti alloy cuttings a n d B ore was investigated. E m b r i t t l e m e n t , boride synthesis conditions a n d effects of c o m p o s i t i o n were studied. The p r o d u c t i o n route is described.
Tungsten D I F F U S I O N B O N D I N G OF TUNGSTENCOPPER TO C O P P E R B A S E D S U B S T R A T E S BY HOT ISOSTATIC PRESSING
T. Anqing, L. Darning (Central Iron a n d Steel Research Inst., Beijing, C h i n a ) , PM Technology, Vol 11, No 4, 1993, 254-259. (In Chinese). It is reported t h a t t h e use of HIP h a d e n a b l e d diffusion b o n d i n g of W-(10 to 40)wt%Cu to Cu or Cu~0.7%Cr. The tensile s t r e n g t h of t h e c o m p o u n d p a r t is shown to a p p r o x i m a t e to t h a t of t h e Cu or Cu-Cr alloy. Problems of b o n d i n g are discussed. The presence of Cr is considered to improve t h e properties of t h e b o n d e d joints.
Electrical and magnetic materials CRYSTALLIZATION OF AMORPHOUS IRON-NICKEL-BORON ALLOYS
S.W. Lee et al ( C h u n g n a m National University, Taejon, Korea), J. Korean Inst. of Metals, Vol 31, No 6, 1993, 748-756. (In Korean). Crystallization of a m o r p h o u s Fe-Ni-B powders was investigated. Activation e n e r g i e s for f o r m a t i o n of c r y s t a l l i n e phases were determined. The phases formed were yFeNi a n d (~ (Fe,Ni)~B. SYNTHESIS AND MAGNETIC PROPI~RTrES OF FINE PARTICLES OF ~IRON CARBIDE
Y. B a n d o et al (Kyoto University, Uji, Kyoto, J a p a n ) , J. Japan Soc. Powder and Powder Metallurgy, Vol 40, No 8, 1993, 823-826. (In J a p a n e s e ) . Production of Fe2.2C of fine powder is described. A hydroxide is reduced in steps to ~:Fe a n d carburized to Fe2.2C. The powder had a saturation magnetization 117 e m u / g m a n d a c o e r c i v e force of 1042 0e.
Hard materials and tool steels INVESTIGATION OF SINTERING OF SPHERICAL HIGH S P E E D S T E E L POWDERS
R.A. Andrievski, N.K. Kasmamytov (Russian Academy of Sciences, Chernogolovka, Moscow, Russia) Powder MetaU. Int., Vol 25, No 6, 1993, 275-277. The effects of time, t e m p e r a t u r e a n d particle radius on t h e rate of increase of imparticle contact d u r i n g v a c u u m sintering of loosely packed spherical powders of high speed steels, m a d e by N atomization, were i n v e s t i g a t e d . A c t i v a t i o n e n e r g i e s were d e t e r m i n e d a n d are discussed. X-ray a n d microprobe studies are r e p o r t e d to p e r m i t discussion of t h e d i s t r i b u t i o n of metallic a n d non-metallic particles in t h e samples. B I N D E R PHASE E N R I C H M E N T BY DISSOLUTION OF CUBIC CARBIDES
P. Gustafson, A. O s t l u n d (AB S a n d v i k C o r o m a n t , Stockholm, Sweden), Int. J. Refractory. Metals & Hard Materials, Vol 12, No 3, 1993-1994, 129-136. It is n o t e d t h a t w h e n a c e m e n t e d c a r b i d e , c o n t a i n i n g N, is s i n t e r e d in v a c u u m or a N-free a t m o s p h e r e a graded zone, free from cubic carbides, forms at the surface. A k i n e t i c / t h e r m o d y n a m i c based model to explain t h i s is presented. The formation of t h e graded zone is a t t r i b u t e d to diffusion of N o u t of t h e c o m p a c t with coupled diffusion of cubic carbide forming e l e m e n t s in t h e reverse direction. The effect of s h a r p edges is e x p l a i n e d t h e gradient. being t h i n n e r close to s h a r p edges. DEVELOPMENT OF CUBIC CARBIDE F R E E SURFACE LAYERS IN N I T R O G E N F R E E C E M E N T E D CARBIDES
W.C. Yohe (Valanite Co[p, Troy, Michigan, USA), Int. J. Refractory Metals & Hard Materials, Vol 12, No 3, 1993-1994, 137144. M o d i f i c a t i o n of s u r f a c e l a y e r s in c e m e n t e d carbides to p r o m o t e additional toughness, is discussed with reference to methods used. Novel methods for d e v e l o p m e n t of carbide free surface layers, w i t h o u t t h e a d d i t i o n of N, are described. The kinetics of f o r m a t i o n are c o m p a r e d for a range of alloy c o m p o s i t i o n s with a n d w i t h o u t N. Effects of c o m p o s i t i o n a n d process conditions are discussed. P R O C E S S I N G OF C E M E N T E D CARBIDES WITH COMPOSITIONAL G R A D I E N T S BY POWDER METALLURGY
C. Colin et al ( C a t h o l i c University of Louvain-la-Neuve, Belgium), Int. J. Refrac tory Metals & Hard Materials, Vol 12, No 3, 1993~1994, 145-152.
MPR December 1994 63
morphology of Fe 1.75%Ni-l.5%Cu-0.5%Mo steels with C is described. Fractures are used to show the heterogeneity of t h e steels a n d this is confirmed by selected area energy dispersive analysis which showed the segregation of t h e alloy elements. SHEAT ROLLING OF WATER ATOMIZED IRON-CHRONIUMALUMINIUM ALLOY POWDERS
I. O h n a k a et al (Osaka University, Suita, Osaka, J a p a n ) , J. Japan Inst. of Metals, Vol 57, No 9, 1993, 1083-1088. (In Japanese). Rapidly solidified Fe-30%Cr-5%Al alloy powders were s h e a t h rolled. As reduction i n c r e a s e d t h e o x i d e films on p a r t i c l e surfaces were f r a g m e n t e d a n d p a r t i c l e b o n d i n g improved. Effects of additions of Ce w e r e s t u d i e d . W i t h o u t Ce t e n s i l e s t r e n g t h increased linearly with reduction in the range 45 to 75%. With Ce t h e tensile s t r e n g t h was found to be low for small restrictions b u t at 60% s t r e n g t h s with a n d without Ce w e r e s i m i l a r . F r a c t u r e characteristics changed from i n t e r g r a n u l a r to t r a n s g r a n u l a r as deformation increased. CHEMICOTHERMAL PROCESSING OF IRON-BASE ALLOY POWDERS
A.P. Epik, M. A d a l l a k h , Poroshkovaya Metallurgiya, No 8, 1993, 37-43. (In Russian). Chromizing a n d boronizing of Fe base powders is described, t h e kinetics of growth of diffusion layers are shown to d e p e n d on diffusion saturation, alloy composition a n d porosity. Mechanical properties were determined. Wear properties are reported to b e e n h a n c e d by c h r o m i z i n g a n d b o r o n i z i n g w i t h o u t i n c r e a s e in o t h e r mechanical properties. Chromizing and b o r o n i z i n g are r e p o r t e d to t a k e 3 to 4 h o u r s at l l00°C a n d 2 to 3 h o u r s at l()00 ~C respectively.
Nickel E F F E C T S OF PRECIPITATES AND OXIDE D I S P E R S O I D S ON CREEP IN NICKEL-CHRONIUM-TUNGSTEN ALLOYS
S.l. Kwun, J.S. Cho (Korea University, Seoul, Korea), J. Korean Inst. of Metals. Vol 31, No 6, 1993, 757-765. (In Korean), High t e m p e r a t u r e tensile a n d creep tests were carried out on Ni-20%Cr-4%W which was s i n t e r e d from m e c h a n i c a l l y alloyed powders. The alloys contained y' precipitates a n d Y20:~ dispersoids. It is r e p o r t e d t h a t zone a n n e a l i n g i n c r e a s e s s t r e n g t h a n d c r e e p r e s i s t a n c e d u e to increased grain size a n d aspect ratio. Y203 acts as a dispersion s t r e n g t h e n i n g a g e n t a n d improves t h e r m a l stability of t h e y' precipitates at high temperatures. Up to
LITERATURE
REVIEW
950"C t h e ¥' precipitates c o n t r i b u t e d more to high t e m p e r a t u r e properties. The Y203 is considered to c o n t r i b u t e more to creep resistance t h a n tensile strength.
Titanium PRODUCTION OF TITANIUM BORIDE POWDERS FROM WASTE MATERIALS
I.V. Sokol et al, Poroshkovaya Metallurgiya, No 8, 1993, 1-7. (In Russian). The possibility of making TiB2 from Ti alloy cuttings a n d B ore was investigated. E m b r i t t l e m e n t , boride synthesis conditions a n d effects of c o m p o s i t i o n were studied. The p r o d u c t i o n route is described.
Tungsten D I F F U S I O N B O N D I N G OF TUNGSTENCOPPER TO C O P P E R B A S E D S U B S T R A T E S BY HOT ISOSTATIC PRESSING
T. Anqing, L. Darning (Central Iron a n d Steel Research Inst., Beijing, C h i n a ) , PM Technology, Vol 11, No 4, 1993, 254-259. (In Chinese). It is reported t h a t t h e use of HIP h a d e n a b l e d diffusion b o n d i n g of W-(10 to 40)wt%Cu to Cu or Cu~0.7%Cr. The tensile s t r e n g t h of t h e c o m p o u n d p a r t is shown to a p p r o x i m a t e to t h a t of t h e Cu or Cu-Cr alloy. Problems of b o n d i n g are discussed. The presence of Cr is considered to improve t h e properties of t h e b o n d e d joints.
Electrical and magnetic materials CRYSTALLIZATION OF AMORPHOUS IRON-NICKEL-BORON ALLOYS
S.W. Lee et al ( C h u n g n a m National University, Taejon, Korea), J. Korean Inst. of Metals, Vol 31, No 6, 1993, 748-756. (In Korean). Crystallization of a m o r p h o u s Fe-Ni-B powders was investigated. Activation e n e r g i e s for f o r m a t i o n of c r y s t a l l i n e phases were determined. The phases formed were yFeNi a n d (~ (Fe,Ni)~B. SYNTHESIS AND MAGNETIC PROPI~RTrES OF FINE PARTICLES OF ~IRON CARBIDE
Y. B a n d o et al (Kyoto University, Uji, Kyoto, J a p a n ) , J. Japan Soc. Powder and Powder Metallurgy, Vol 40, No 8, 1993, 823-826. (In J a p a n e s e ) . Production of Fe2.2C of fine powder is described. A hydroxide is reduced in steps to ~:Fe a n d carburized to Fe2.2C. The powder had a saturation magnetization 117 e m u / g m a n d a c o e r c i v e force of 1042 0e.
Hard materials and tool steels INVESTIGATION OF SINTERING OF SPHERICAL HIGH S P E E D S T E E L POWDERS
R.A. Andrievski, N.K. Kasmamytov (Russian Academy of Sciences, Chernogolovka, Moscow, Russia) Powder MetaU. Int., Vol 25, No 6, 1993, 275-277. The effects of time, t e m p e r a t u r e a n d particle radius on t h e rate of increase of imparticle contact d u r i n g v a c u u m sintering of loosely packed spherical powders of high speed steels, m a d e by N atomization, were i n v e s t i g a t e d . A c t i v a t i o n e n e r g i e s were d e t e r m i n e d a n d are discussed. X-ray a n d microprobe studies are r e p o r t e d to p e r m i t discussion of t h e d i s t r i b u t i o n of metallic a n d non-metallic particles in t h e samples. B I N D E R PHASE E N R I C H M E N T BY DISSOLUTION OF CUBIC CARBIDES
P. Gustafson, A. O s t l u n d (AB S a n d v i k C o r o m a n t , Stockholm, Sweden), Int. J. Refractory. Metals & Hard Materials, Vol 12, No 3, 1993-1994, 129-136. It is n o t e d t h a t w h e n a c e m e n t e d c a r b i d e , c o n t a i n i n g N, is s i n t e r e d in v a c u u m or a N-free a t m o s p h e r e a graded zone, free from cubic carbides, forms at the surface. A k i n e t i c / t h e r m o d y n a m i c based model to explain t h i s is presented. The formation of t h e graded zone is a t t r i b u t e d to diffusion of N o u t of t h e c o m p a c t with coupled diffusion of cubic carbide forming e l e m e n t s in t h e reverse direction. The effect of s h a r p edges is e x p l a i n e d t h e gradient. being t h i n n e r close to s h a r p edges. DEVELOPMENT OF CUBIC CARBIDE F R E E SURFACE LAYERS IN N I T R O G E N F R E E C E M E N T E D CARBIDES
W.C. Yohe (Valanite Co[p, Troy, Michigan, USA), Int. J. Refractory Metals & Hard Materials, Vol 12, No 3, 1993-1994, 137144. M o d i f i c a t i o n of s u r f a c e l a y e r s in c e m e n t e d carbides to p r o m o t e additional toughness, is discussed with reference to methods used. Novel methods for d e v e l o p m e n t of carbide free surface layers, w i t h o u t t h e a d d i t i o n of N, are described. The kinetics of f o r m a t i o n are c o m p a r e d for a range of alloy c o m p o s i t i o n s with a n d w i t h o u t N. Effects of c o m p o s i t i o n a n d process conditions are discussed. P R O C E S S I N G OF C E M E N T E D CARBIDES WITH COMPOSITIONAL G R A D I E N T S BY POWDER METALLURGY
C. Colin et al ( C a t h o l i c University of Louvain-la-Neuve, Belgium), Int. J. Refrac tory Metals & Hard Materials, Vol 12, No 3, 1993~1994, 145-152.
MPR December 1994 63