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A study of amorphization in iron-carbon alloys
liquid a n d solid states a n d t h e h e a t of mixing is positive. MA is shown to induce solubility of Cu in W a n d W in Cu. Lattice p a r a m e t e r s were m e a s u r e d for 5 to 95at%W. A m o r p h o u s p h a s e s were detected. It is suggested that the mechanism of amorphization differs from so-called classical a m o r p h i z a t i o n . A STUDY O F A M O R P H I Z A T I O N IN IRON-
differential s c a n n i n g calorimetry, for t h e d e t e r m i n a t i o n of H is described, M~rAL ~NJ~C'F]~ON MOULDING . . . . . . . . B I N D E R E X T R A C T I O N FROM I N J E C T I O N M O U L D E D CERAMIC PARTS
CARBON ALLOYS T.Nasu et al. (North Carolina State University, USA.) Materials Science and Engineering A, Vol A134, 1991, 1385-1388. Mechanical alloying of Fe-25at%C is s h o w n to r e s u l t in a m o r p h i z a t i o n . The s o l u t i o n of C in Fe is d i s o r d e r e d b u t contains d o m a i n s equivalent to cementite, Fe3C. A M O R P H I Z A T I O N O F NICKELZIRCONIUM ALLOYS BY MECHANICAL ALLOYING J.Eckert et al. (Kernforschungsanlage Jfilich, Jfilich, Germany.) Materials Science and Engineering A, Vol A134, 1991, 13891393. An investigation of the effects of MA on Ni-Zr alloys is described. F o r m a t i o n of t h e amorphous phase at inter-elemental interfaces in t h e initial stages of MA is reported a n d e x t e n d e d MA results in full amorphization. It is suggested t h a t MA prevents the formation of NiZr i n t e r m e d i a t e p h a s e s d u r i n g interdiffusion of Ni a n d Zr. MECHANICAL ALLOYING BY BALL MILLING OF IRON-SILICON ALLOYS A.G.Escorial et al, Materials Science and Engineering A, VolA134, 1991, 1394-1397. The p h a s e s formed d u r i n g MA of Fe-(5 to 50)at%Si alloys were d e t e r m i n e d by Xray diffraction, scanning electron microscopy, differential scanning calorimeter a n d m a g n e t i c m e a s u r e m e n t s . An evaluation of t h e p r o p o r t i o n s of t h e p h a s e s found is given.
K.Saltoh et al. (Inst. of Industrial Research, Kyoto, J a p a n . ) J.Japan Soc. Powder and Powder Metallurgy, Vol. 38, No 5, 11991, 627-629. (In J a p a n e s e . ) T h e r e m o v a l of a b i n d e r m i x t u r e , consisting of polyethylene, polypropylene a n d vegetable oil, from injection m o u l d e d A12Oa p a r t s w a s i n v e s t i g a t e d . S o l v e n t e x t r a c t i o n with acetone at 23°C removed 78% of t h e oil after 6 h o u r s immersion. The r e s i d u e of t h e b i n d e r w a s r e m o v e d t h e r m a l l y a t 420°C for 2 h o u r s a f t e r h e a t i n g a t 2.5°C/min to 50°C a n d 1OO°C/ h o u r to 420°C. P a r t s were s i n t e r e d a t 1620°C for 2 h o u r s a n d a density of 99% is reported, THERMAL D E B I N D I N G IN METAL I N J E C T I O N MOULDING ( M I M ) S.C.Lin et al. (Industrial Technology Research Institute, Taiwan.) MRL Bull.Research andDevelopment, Vol 4, No 2, 1990, 101-105. Thermogravimetric analysis (TGA) was u s e d to s t u d y t h e d e b i n d i n g of MIM carbonyl FE c o m p a c t s w i t h t h r e e b i n d e r systems a n d to d e t e r m i n e t h e o p t i m u m conditions for debinding. Parts were t h e n v a c u u m d e b o u n d a n d it was f o u n d t h e fine d e b o u n d p a r t s could be o b t a i n e d a t a h e a t i n g rate of 5°C/min a n d t h e s e h a d a d e n s i t y of 91%. T h e m e c h a n i s m s o f debinding defect formation was also studied. It was e s t a b l i s h e d t h a t h e initial wicking p a t h formed a t a n early stage in t h e d e b i n d i n g was t h e critical stage. P~
M.Baricco et al. (University of Turin, Turin, Italy.) Materials Science and Engineering A, VolA134, 1398-1401. C u ( 4 0 , 50 o r 6 0 ) a t % t i powders subjected to ballmilling were characterised. The effects of H originating i n t h e Ti o n a m o r p h i z a t i o n and crystallization processes are described. For Cu-Ti a diffusion controlled process of amorphization is i n f e r r e d f r o m t h e parabolic form of the heat of r e c r y s t a l l i z a t i o n / m i l l i n g curve. T h e H m o d i f i e s t h e r e c r y s t a l l i z a t i o n of t h e a m o r p h o u s phase. A method, b a s e d o n
INVESTIGATION O F S I N T E R E D S T E L L I T E L VALVE SEATS FOR INTERNAL C O M B U S T I O N ( I C ) ENGINES J.Michalowski, J.Pietaszewski. (Wojskowa A k a d e m i a T e c h n i c z n a , Warsaw, Poland. Metalurgia proszkow, Vol 24, No 2, 1991, 49-52. (In Polish.) An investigation, a n d the results there, of t h e m a n u f a c t u r e of stellite IC engine valve seats, by pressing a n d sintering, are presented. SURFACE DURABILITY O F T H R O U G H PM GEARS C.Madhavean, K.Gopinath. (Indian I n s t i t u t e of Technology, Madras, India.) Powder Metallurgy Science and Technology, Vol 2, No 4, 1991, 30-44. An investigation of t h e durability of t h r o u g h h a r d e n e d PM gears a n d a test rig for this are described. Surface conditions were m o n i t o r e d by t o o t h thickness, weight loss, surface profile, acoustic levels a n d l u b r i c a n t analysis. The oil film thickness u n d e r o p e r a t i n g conditions was e s t i m a t e d to be 1 pm. Before t h e o n s e t of pitting t h e r e was mild adhesive wear a n d s u b s e q u e n t l y t h e r e is severe wear due to surface fatigue. An e q u a t i o n for t h e prediction of gear life is deduced and failure analysis and m e c h a n i s m s are discussed. R~ff~AC]rO~
' ~ r ~ . s
-HIGH TEMPERATURE APPLICATIONS O F REFRACTORY METALS
p~]rS --
THERMAL BEHAVIOUR O F COPPERTITANIUM AND COPPER-TITANIUMHYDROGEN BALL M I L L E D POWDERS
The d e v e l o p m e n t of a process route for t h e p r o d u c t i o n of conical p a r t s from Fe powder is described. The process steps are: compaction a n d sintering of a preform, a n d hot forging of t h e preform in conical dies on a c r a n k press. New die designs, to give o p t i m u m d i m e n s i o n s to t h e f i n i s h e d product, are outlined.
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P R O D U C T I O N O F SEMIC I R C U M F E R E N C E T A P E R E D GEAR WITH DOUBLE BOSS S.Xiaofang. ( S h a n g h a i Powder Metallurgy Works, Shanghai, China.) PM Technology, Vol 9, No 4, 1991, 206-208. (In Chinese.) The p a p e r deals with m a t e r i a l s selection, die design and forming of semicircumferential tapered hear with a d o u b l e boss. The c o m p o n e n t a n d die assembly are illustrated, C O M P A C T I N G CONIC B U S H E S F R O M POWDER P R E F O R M S L.A.Barkov et al. Kuznechno-Shtampov, Pro/z., No 11, 1990, 4~5. (In Russian.)
J.G.Heyes, R.G.R.Sellors. (Plansee Metals Ltd., Slough, England.) Metals and Materials, Vol 8, No 2, 1992, 86-92. The commercial applications of refractory metals, W, Mo, Ta a n d Nb are reviewed. It is considered t h a t t h e o t h e r m e t a l s with melting points above 2000°C, Hf, Re, Os, Ir a n d Os, are too rare a n d to find o t h e r t h a n very limited use. PM is used extensively in t h e fabrication of W, Mo, Nb a n d T a b u t special melting p r o c e d u r e s are used to produce ingot metal. The properties, strength and hardness, corrosion a n d o x i d a t i o n r e s i s t a n c e a n d high density a n d low t h e r m a l expansion, are d i s c u s s e d . A p p l i c a t i o n s c o n s i d e r e d include lighting technology, high t e m p e r a t u r e furnaces, tooling for h i g h temperature mechanical working processes a n d X-ray technology hardware.
MPR April 1992 55
differential s c a n n i n g calorimetry, for t h e d e t e r m i n a t i o n of H is described, M~rAL ~NJ~C'F]~ON MOULDING . . . . . . . . B I N D E R E X T R A C T I O N FROM I N J E C T I O N M O U L D E D CERAMIC PARTS
CARBON ALLOYS T.Nasu et al. (North Carolina State University, USA.) Materials Science and Engineering A, Vol A134, 1991, 1385-1388. Mechanical alloying of Fe-25at%C is s h o w n to r e s u l t in a m o r p h i z a t i o n . The s o l u t i o n of C in Fe is d i s o r d e r e d b u t contains d o m a i n s equivalent to cementite, Fe3C. A M O R P H I Z A T I O N O F NICKELZIRCONIUM ALLOYS BY MECHANICAL ALLOYING J.Eckert et al. (Kernforschungsanlage Jfilich, Jfilich, Germany.) Materials Science and Engineering A, Vol A134, 1991, 13891393. An investigation of the effects of MA on Ni-Zr alloys is described. F o r m a t i o n of t h e amorphous phase at inter-elemental interfaces in t h e initial stages of MA is reported a n d e x t e n d e d MA results in full amorphization. It is suggested t h a t MA prevents the formation of NiZr i n t e r m e d i a t e p h a s e s d u r i n g interdiffusion of Ni a n d Zr. MECHANICAL ALLOYING BY BALL MILLING OF IRON-SILICON ALLOYS A.G.Escorial et al, Materials Science and Engineering A, VolA134, 1991, 1394-1397. The p h a s e s formed d u r i n g MA of Fe-(5 to 50)at%Si alloys were d e t e r m i n e d by Xray diffraction, scanning electron microscopy, differential scanning calorimeter a n d m a g n e t i c m e a s u r e m e n t s . An evaluation of t h e p r o p o r t i o n s of t h e p h a s e s found is given.
K.Saltoh et al. (Inst. of Industrial Research, Kyoto, J a p a n . ) J.Japan Soc. Powder and Powder Metallurgy, Vol. 38, No 5, 11991, 627-629. (In J a p a n e s e . ) T h e r e m o v a l of a b i n d e r m i x t u r e , consisting of polyethylene, polypropylene a n d vegetable oil, from injection m o u l d e d A12Oa p a r t s w a s i n v e s t i g a t e d . S o l v e n t e x t r a c t i o n with acetone at 23°C removed 78% of t h e oil after 6 h o u r s immersion. The r e s i d u e of t h e b i n d e r w a s r e m o v e d t h e r m a l l y a t 420°C for 2 h o u r s a f t e r h e a t i n g a t 2.5°C/min to 50°C a n d 1OO°C/ h o u r to 420°C. P a r t s were s i n t e r e d a t 1620°C for 2 h o u r s a n d a density of 99% is reported, THERMAL D E B I N D I N G IN METAL I N J E C T I O N MOULDING ( M I M ) S.C.Lin et al. (Industrial Technology Research Institute, Taiwan.) MRL Bull.Research andDevelopment, Vol 4, No 2, 1990, 101-105. Thermogravimetric analysis (TGA) was u s e d to s t u d y t h e d e b i n d i n g of MIM carbonyl FE c o m p a c t s w i t h t h r e e b i n d e r systems a n d to d e t e r m i n e t h e o p t i m u m conditions for debinding. Parts were t h e n v a c u u m d e b o u n d a n d it was f o u n d t h e fine d e b o u n d p a r t s could be o b t a i n e d a t a h e a t i n g rate of 5°C/min a n d t h e s e h a d a d e n s i t y of 91%. T h e m e c h a n i s m s o f debinding defect formation was also studied. It was e s t a b l i s h e d t h a t h e initial wicking p a t h formed a t a n early stage in t h e d e b i n d i n g was t h e critical stage. P~
M.Baricco et al. (University of Turin, Turin, Italy.) Materials Science and Engineering A, VolA134, 1398-1401. C u ( 4 0 , 50 o r 6 0 ) a t % t i powders subjected to ballmilling were characterised. The effects of H originating i n t h e Ti o n a m o r p h i z a t i o n and crystallization processes are described. For Cu-Ti a diffusion controlled process of amorphization is i n f e r r e d f r o m t h e parabolic form of the heat of r e c r y s t a l l i z a t i o n / m i l l i n g curve. T h e H m o d i f i e s t h e r e c r y s t a l l i z a t i o n of t h e a m o r p h o u s phase. A method, b a s e d o n
INVESTIGATION O F S I N T E R E D S T E L L I T E L VALVE SEATS FOR INTERNAL C O M B U S T I O N ( I C ) ENGINES J.Michalowski, J.Pietaszewski. (Wojskowa A k a d e m i a T e c h n i c z n a , Warsaw, Poland. Metalurgia proszkow, Vol 24, No 2, 1991, 49-52. (In Polish.) An investigation, a n d the results there, of t h e m a n u f a c t u r e of stellite IC engine valve seats, by pressing a n d sintering, are presented. SURFACE DURABILITY O F T H R O U G H PM GEARS C.Madhavean, K.Gopinath. (Indian I n s t i t u t e of Technology, Madras, India.) Powder Metallurgy Science and Technology, Vol 2, No 4, 1991, 30-44. An investigation of t h e durability of t h r o u g h h a r d e n e d PM gears a n d a test rig for this are described. Surface conditions were m o n i t o r e d by t o o t h thickness, weight loss, surface profile, acoustic levels a n d l u b r i c a n t analysis. The oil film thickness u n d e r o p e r a t i n g conditions was e s t i m a t e d to be 1 pm. Before t h e o n s e t of pitting t h e r e was mild adhesive wear a n d s u b s e q u e n t l y t h e r e is severe wear due to surface fatigue. An e q u a t i o n for t h e prediction of gear life is deduced and failure analysis and m e c h a n i s m s are discussed. R~ff~AC]rO~
' ~ r ~ . s
-HIGH TEMPERATURE APPLICATIONS O F REFRACTORY METALS
p~]rS --
THERMAL BEHAVIOUR O F COPPERTITANIUM AND COPPER-TITANIUMHYDROGEN BALL M I L L E D POWDERS
The d e v e l o p m e n t of a process route for t h e p r o d u c t i o n of conical p a r t s from Fe powder is described. The process steps are: compaction a n d sintering of a preform, a n d hot forging of t h e preform in conical dies on a c r a n k press. New die designs, to give o p t i m u m d i m e n s i o n s to t h e f i n i s h e d product, are outlined.
:
__
__
P R O D U C T I O N O F SEMIC I R C U M F E R E N C E T A P E R E D GEAR WITH DOUBLE BOSS S.Xiaofang. ( S h a n g h a i Powder Metallurgy Works, Shanghai, China.) PM Technology, Vol 9, No 4, 1991, 206-208. (In Chinese.) The p a p e r deals with m a t e r i a l s selection, die design and forming of semicircumferential tapered hear with a d o u b l e boss. The c o m p o n e n t a n d die assembly are illustrated, C O M P A C T I N G CONIC B U S H E S F R O M POWDER P R E F O R M S L.A.Barkov et al. Kuznechno-Shtampov, Pro/z., No 11, 1990, 4~5. (In Russian.)
J.G.Heyes, R.G.R.Sellors. (Plansee Metals Ltd., Slough, England.) Metals and Materials, Vol 8, No 2, 1992, 86-92. The commercial applications of refractory metals, W, Mo, Ta a n d Nb are reviewed. It is considered t h a t t h e o t h e r m e t a l s with melting points above 2000°C, Hf, Re, Os, Ir a n d Os, are too rare a n d to find o t h e r t h a n very limited use. PM is used extensively in t h e fabrication of W, Mo, Nb a n d T a b u t special melting p r o c e d u r e s are used to produce ingot metal. The properties, strength and hardness, corrosion a n d o x i d a t i o n r e s i s t a n c e a n d high density a n d low t h e r m a l expansion, are d i s c u s s e d . A p p l i c a t i o n s c o n s i d e r e d include lighting technology, high t e m p e r a t u r e furnaces, tooling for h i g h temperature mechanical working processes a n d X-ray technology hardware.
MPR April 1992 55