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Sintering of ultrafine Mo powder compacts
microcrystalline p a r t s by h o t extrusion. The m a i n difference between w a t e r a n d gas atomized powders was surface i r r e g u l a r i t i e s . P a r t i c l e s 10}~m is size generally c o n t a i n e d one crystal b u t larger particles were polycrystalline.
PARTIALLY ALLOYED IRON POWDERS L.V. Nikoforov, et al, Aytom. Prom-st, No 4, 1990, 26-28. In Russian. S t r u c t u r a l studies of a n Fe base powder c o n t a i n i n g Cu a n d Mo, showed spongy particles and intraparticle pores. C o m p a c t i n g was found to d e p e n d strongly o n pressure. The effect of Cu on sintering is discussed. Operating time a n d t e m p e r a t u r e , a n d mechanical p r o p e r t i e s are given.
STRUCTURE A N D P R O P E R T I E S OF ALLOYED F e POWDERS A N D S I N T E R E D ARTICLES H. Frydrych, et al, Rudy Met. Niezelaz, Vol 35, No 4, 1990, 90-95. In Polish. A s t u d y of Fe base powders a n d sintered materials was undertaken with the objective of optimizing t h e a d d i t i o n s of Cu, Mo a n d Ni. Properties of Fe-l.5%Cu1.75%Ni-0.5%Mo w e r e m e a s u r e d a n d s t r u c t u r a l a n a l y s i s was c a r r i e d o u t in o r d e r to d e t e r m i n e t h e d i s t r i b u t i o n of t h e alloy elements.
H O M O G E N I Z A T I O N O F Ni BEARING PM STEELS N.V. Krokhina, et al, Izv. Akad. Nauk. SSSR Met, No 4, 1990, 84-87. In Russian. The a d d i t i o n of NiO powder to steel powder i n s t e a d of Ni is shown to accelerate t h e dissolution of Ni in t h e steel, a n d c o n t r i b u t e t o t h e h o m o g e n i z a t i o n of composition a n d s t r u c t u r e . T h i s is a t t r i b u t e d to t h e h i g h e r defect density a n d dispersivity of t h e NiO particles a n d t h e larger surface c o n t a c t a r e a between Ni a n d Fe particles.
S T R U C T U R E A N D P R O P E R T I E S OF PM MATERIALS B A S E D ON A CORROSION R E S I S T A N T STEEL
Molybdenum I
INTERGRANULAR S E G R E G A T I O N A N D FRACTURE IN M o Y. Hiraoka, et al, (Okayama University of Science, Okayama, J a p a n ) , J. Japan Inst. of Metals, Vol 54, No 11, 1990, 1205-1213. In Japanese. T h e e f f e c t of N o n i n t e r g r a n u l a r segregation a n d fracture properties of Mo have b e e n investigated. Samples of Mo exhibiting t h e ' b a m b o o ' type of s t r u c t u r e were doped with N to various c o n c e n t r a t i o n s . It was f o u n d t h a t t h e driving force for 0 segregation was greater t h a n t h a t for N in t h e range 1600 to 1960°C a n d t h a t O segregation is e n h a n c e d by N. Fracture energy decreased with increased 0 a n d N segregation a n d it was suggested t h a t t h e fracture energy was related to t h e geometrical n a t u r e of t h e grain boundaries. S I N T E R I N G OF ULTRAFINE Mo POWDER COMPACTS tLU. Kalamazov, et al, P/z. Chim Obrab. Mater, No 5, 1989, 130-133. In Russian. The sintering of ultrafine Mo powder in v a c u u m was studied w i t h t h e objective of a t t a i n i n g full density. It was found t h a t in o r d e r to r e a c h full density it was necessary to a n n e a l t h e Mo powder a t 600°C for two h o u r s in H prior to compacting.
Nickel
E F F E C T S OF HEAT T R E A T M E N T AND HIP ON C R E E P P R O P E R T I E S OF NiBASE SUPERALLOY IN713LC Y.S. Kim, et ai, (Chosan University, Kwang Ju, Korea), J. Korean Inst. of Metals, Vol 28, No 10, 1990, 866-872. In Korean. The c r e e p p r o p e r t i e s of a Ni b a s e superalloy were studied with reference to t h e r o l e of c a r b i d e s , HIP a n d h e a t t r e a t m e n t . Increase in solution t r e a t m e n t t e m p e r a t u r e gave a n increase in r u p t u r e life. Carbide morphologies were d e t e r m i n e d a n d changes were detected. MICROSTRUCTURE A N D PHASE C O M P O S I T I O N OF Ni-BASE SUPERALLOY POWDER B. Hu, et al, (University of Science a n d Technology, Beijing, China), Acta MetaUurgica Sinica, Vol 26, No 5, 1990, A334-339. In Chinese. The microstructure and phase c o m p o s i t i o n of a Ni b a s e s u p e r a l l o y , FGH95, powder of differing size fractions were studied. As particle size d i m i n i s h e d t h e s t r u c t u r e showed a c h a n g e from a dendritic s t r u c t u r e to a cellular one. The main secondary phases present were carbides. Other p h a s e s detected included Laves phases, primary y' a n d borides. KINETICS OF GRAIN GROWTH IN A NiBASE SUPERALLOY
ELASTIC P R O P E R T I E S OF PM INVAR ALLOYS V.A. V e r s h i n i n , e t al, P o r o s h k a v a y a MetaUurgiya, No 9, 1990. In Russian. E l a s t i c c o n s t a n t s a n d t h e r a t e of supersonic wave p r o p a g a t i o n in PM Invar were m e a s u r e d by dynamic m e t h o d s in t h e t e m p e r a t u r e range -100 to + 500°C. Fair correlation between elasticity a n d t h e r m a l e x p a n s i o n is reported. P R O P E R T I E S O F PM Ni-BASE SUPERALLOY DUAL-PROPERTY D I S C S P R O D U C E D BY SUPERPLASTIC FORGING O. Tsuda,
S.N. Boshin, S.R. Nezamaev, Metalloved. Term Obrab. Met, No 8, 1990, 50-51. In Russian. The p r o p e r t i e s a n d s t r u c t u r e of a corrosion r e s i s t a n t steel with additions of graphite, Mo, Ti a n d W2S were investigated. After pressing a t 600 to 800 N / m m 2 a n d sintering at l l 0 0 ° C in H2 t h e r e was 10% porosity a n d Brinell h a r d n e s s 120 to 130. 2% oil could be infiltrated into t h e material. The s t r u c t u r e s c o n t a i n e d austenite, a Morich phase, ferrite, carbides a n d u n c h a n g e d steel powder, according to composition. The alloys h a d low friction.
I
s t r u c t u r e a n d t h e bore was fine grained. Use in a n e x p e r i m e n t a l t u r b i n e w a s reported.
et al,
Z. Huda, B. Ralph, ( B r u n e l University, Uxbridge, UK), Materials Character/sation, Vol 25, No 2, 1990, 211-220. Grain growth in a Ni base superalloy, IN792, in a new modified form APK6, h a s been investigated. Thermodynamic quantities, activation energies, were determined. Anomalous grain growth was observed after annealing a t 1270°C for 22 hours and mean and maximum grain diameters m e a s u r e d were 60 a n d 85~m respectively. It is s u g g e s t e d t h a t t h e m a t e r i a l m a y find a p p l i c a t i o n s in gas t u r b i n e blades.
(Kobe Steel, J a p a n ) ,
Kobelco Technology Review, No 9, 1990, 38-42. The p r o d u c t i o n of t u r b i n e discs, 400 m m in diameter, in which different PM materials are used in different sections of t h e disc is described. The rim is of a material with superior stress r u p t u r e characteristics a n d t h e bore region is a n alloy with high tensile s t r e n g t h a n d low cycle fatigue life. A two step HIP process was followed by superplastic forging. Gas atomized powders were used. The disc was f o u n d to b e well consolidated. After h e a t t r e a t m e n t t h e rim w a s f o u n d to h a v e a c o a r s e g r a i n e d
E F F E C T OF P R O C E S S VARIABLES ON STRUCTURE A N D MAGNETIC P R O P E R T I E S O F ULTRAFINE Ni A N D Ni-AI POWDERS ALL. Berezina, et al, (Inst. of Metal Physics, Kiev, USSR), Metallofizika, Vol 12, No 3, 1990, 102-106. In Russian. The structure, p h a s e composition a n d magnetic properties of ultraline Ni a n d Ni6.7wt%A1 powders were investigated as a function of process parameters (electrospark discharge or gas c o n d e n s a t i o n in a n inert m e d i u m ) . The
MPR May 1991 73
PARTIALLY ALLOYED IRON POWDERS L.V. Nikoforov, et al, Aytom. Prom-st, No 4, 1990, 26-28. In Russian. S t r u c t u r a l studies of a n Fe base powder c o n t a i n i n g Cu a n d Mo, showed spongy particles and intraparticle pores. C o m p a c t i n g was found to d e p e n d strongly o n pressure. The effect of Cu on sintering is discussed. Operating time a n d t e m p e r a t u r e , a n d mechanical p r o p e r t i e s are given.
STRUCTURE A N D P R O P E R T I E S OF ALLOYED F e POWDERS A N D S I N T E R E D ARTICLES H. Frydrych, et al, Rudy Met. Niezelaz, Vol 35, No 4, 1990, 90-95. In Polish. A s t u d y of Fe base powders a n d sintered materials was undertaken with the objective of optimizing t h e a d d i t i o n s of Cu, Mo a n d Ni. Properties of Fe-l.5%Cu1.75%Ni-0.5%Mo w e r e m e a s u r e d a n d s t r u c t u r a l a n a l y s i s was c a r r i e d o u t in o r d e r to d e t e r m i n e t h e d i s t r i b u t i o n of t h e alloy elements.
H O M O G E N I Z A T I O N O F Ni BEARING PM STEELS N.V. Krokhina, et al, Izv. Akad. Nauk. SSSR Met, No 4, 1990, 84-87. In Russian. The a d d i t i o n of NiO powder to steel powder i n s t e a d of Ni is shown to accelerate t h e dissolution of Ni in t h e steel, a n d c o n t r i b u t e t o t h e h o m o g e n i z a t i o n of composition a n d s t r u c t u r e . T h i s is a t t r i b u t e d to t h e h i g h e r defect density a n d dispersivity of t h e NiO particles a n d t h e larger surface c o n t a c t a r e a between Ni a n d Fe particles.
S T R U C T U R E A N D P R O P E R T I E S OF PM MATERIALS B A S E D ON A CORROSION R E S I S T A N T STEEL
Molybdenum I
INTERGRANULAR S E G R E G A T I O N A N D FRACTURE IN M o Y. Hiraoka, et al, (Okayama University of Science, Okayama, J a p a n ) , J. Japan Inst. of Metals, Vol 54, No 11, 1990, 1205-1213. In Japanese. T h e e f f e c t of N o n i n t e r g r a n u l a r segregation a n d fracture properties of Mo have b e e n investigated. Samples of Mo exhibiting t h e ' b a m b o o ' type of s t r u c t u r e were doped with N to various c o n c e n t r a t i o n s . It was f o u n d t h a t t h e driving force for 0 segregation was greater t h a n t h a t for N in t h e range 1600 to 1960°C a n d t h a t O segregation is e n h a n c e d by N. Fracture energy decreased with increased 0 a n d N segregation a n d it was suggested t h a t t h e fracture energy was related to t h e geometrical n a t u r e of t h e grain boundaries. S I N T E R I N G OF ULTRAFINE Mo POWDER COMPACTS tLU. Kalamazov, et al, P/z. Chim Obrab. Mater, No 5, 1989, 130-133. In Russian. The sintering of ultrafine Mo powder in v a c u u m was studied w i t h t h e objective of a t t a i n i n g full density. It was found t h a t in o r d e r to r e a c h full density it was necessary to a n n e a l t h e Mo powder a t 600°C for two h o u r s in H prior to compacting.
Nickel
E F F E C T S OF HEAT T R E A T M E N T AND HIP ON C R E E P P R O P E R T I E S OF NiBASE SUPERALLOY IN713LC Y.S. Kim, et ai, (Chosan University, Kwang Ju, Korea), J. Korean Inst. of Metals, Vol 28, No 10, 1990, 866-872. In Korean. The c r e e p p r o p e r t i e s of a Ni b a s e superalloy were studied with reference to t h e r o l e of c a r b i d e s , HIP a n d h e a t t r e a t m e n t . Increase in solution t r e a t m e n t t e m p e r a t u r e gave a n increase in r u p t u r e life. Carbide morphologies were d e t e r m i n e d a n d changes were detected. MICROSTRUCTURE A N D PHASE C O M P O S I T I O N OF Ni-BASE SUPERALLOY POWDER B. Hu, et al, (University of Science a n d Technology, Beijing, China), Acta MetaUurgica Sinica, Vol 26, No 5, 1990, A334-339. In Chinese. The microstructure and phase c o m p o s i t i o n of a Ni b a s e s u p e r a l l o y , FGH95, powder of differing size fractions were studied. As particle size d i m i n i s h e d t h e s t r u c t u r e showed a c h a n g e from a dendritic s t r u c t u r e to a cellular one. The main secondary phases present were carbides. Other p h a s e s detected included Laves phases, primary y' a n d borides. KINETICS OF GRAIN GROWTH IN A NiBASE SUPERALLOY
ELASTIC P R O P E R T I E S OF PM INVAR ALLOYS V.A. V e r s h i n i n , e t al, P o r o s h k a v a y a MetaUurgiya, No 9, 1990. In Russian. E l a s t i c c o n s t a n t s a n d t h e r a t e of supersonic wave p r o p a g a t i o n in PM Invar were m e a s u r e d by dynamic m e t h o d s in t h e t e m p e r a t u r e range -100 to + 500°C. Fair correlation between elasticity a n d t h e r m a l e x p a n s i o n is reported. P R O P E R T I E S O F PM Ni-BASE SUPERALLOY DUAL-PROPERTY D I S C S P R O D U C E D BY SUPERPLASTIC FORGING O. Tsuda,
S.N. Boshin, S.R. Nezamaev, Metalloved. Term Obrab. Met, No 8, 1990, 50-51. In Russian. The p r o p e r t i e s a n d s t r u c t u r e of a corrosion r e s i s t a n t steel with additions of graphite, Mo, Ti a n d W2S were investigated. After pressing a t 600 to 800 N / m m 2 a n d sintering at l l 0 0 ° C in H2 t h e r e was 10% porosity a n d Brinell h a r d n e s s 120 to 130. 2% oil could be infiltrated into t h e material. The s t r u c t u r e s c o n t a i n e d austenite, a Morich phase, ferrite, carbides a n d u n c h a n g e d steel powder, according to composition. The alloys h a d low friction.
I
s t r u c t u r e a n d t h e bore was fine grained. Use in a n e x p e r i m e n t a l t u r b i n e w a s reported.
et al,
Z. Huda, B. Ralph, ( B r u n e l University, Uxbridge, UK), Materials Character/sation, Vol 25, No 2, 1990, 211-220. Grain growth in a Ni base superalloy, IN792, in a new modified form APK6, h a s been investigated. Thermodynamic quantities, activation energies, were determined. Anomalous grain growth was observed after annealing a t 1270°C for 22 hours and mean and maximum grain diameters m e a s u r e d were 60 a n d 85~m respectively. It is s u g g e s t e d t h a t t h e m a t e r i a l m a y find a p p l i c a t i o n s in gas t u r b i n e blades.
(Kobe Steel, J a p a n ) ,
Kobelco Technology Review, No 9, 1990, 38-42. The p r o d u c t i o n of t u r b i n e discs, 400 m m in diameter, in which different PM materials are used in different sections of t h e disc is described. The rim is of a material with superior stress r u p t u r e characteristics a n d t h e bore region is a n alloy with high tensile s t r e n g t h a n d low cycle fatigue life. A two step HIP process was followed by superplastic forging. Gas atomized powders were used. The disc was f o u n d to b e well consolidated. After h e a t t r e a t m e n t t h e rim w a s f o u n d to h a v e a c o a r s e g r a i n e d
E F F E C T OF P R O C E S S VARIABLES ON STRUCTURE A N D MAGNETIC P R O P E R T I E S O F ULTRAFINE Ni A N D Ni-AI POWDERS ALL. Berezina, et al, (Inst. of Metal Physics, Kiev, USSR), Metallofizika, Vol 12, No 3, 1990, 102-106. In Russian. The structure, p h a s e composition a n d magnetic properties of ultraline Ni a n d Ni6.7wt%A1 powders were investigated as a function of process parameters (electrospark discharge or gas c o n d e n s a t i o n in a n inert m e d i u m ) . The
MPR May 1991 73