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Effects of milling conditions on particle sizes in mechanically alloyed powders
PM A m a t h e m a t i c a l analysis of t h e results of transverse r u p t u r e testing of a h a r d m e t a l is p r e s e n t e d . T h e t e s t m e t h o d s a r e described a n d t h e physical significance is discussed. It is shown t h a t t h e statistical p a r a m e t e r s c a n be u s e d to e s t a b l i s h confidence in t h e test results. HARD METALS OF THE NEW GENERATION
H. Kolaska, P e t t m a y e r , ( K r u p p W i d i a GmbH, Essen, Germany), MetaU., Vol 47, No 10, 1993, 908-914. (In G e r m a n ) . An historical review of t h e d e v e l o p m e n t of h a r d metal, for cutting tools a n d wear r e s i s t a n t applications, is presented. It is shown t h a t m o d e r n t r e n d s are towards g r e a t e r h o m o g e n e i t y a n d to i m p r o v e d optimization of processes a n d products. Ultrafine grain h a r d m e t a l s a n d cermets a r e a n n o t a t e d a n d t r e n d s in c o a t i n g technology are outlined in t h e light of t h e changes in m a n u f a c t u r i n g technology. A STUDY OF THE SINTERING BEHAVIOUR OF T U N G S T E N CARBIDENICKEL CARBIDE
H-Y. Lee, W-K. Park, ( I n H a University, Incheon, Korea), J. Korean Inst. of Metals, Vol 31, No 2, 1993, 201-207. (In Korean). The effects of applying a SiC coating to WC powder, in a n a t t e m p t to replace Co in WC c e m e n t e d c a r b i d e s b y Ni, w e r e investigated. Density, m i c r o s t r u c t u r e a n d p o r e d i s t r i b u t i o n w e r e d e t e r m i n e d as functions of t h e a m o u n t of SiC added. SiC is r e p o r t e d to i n h i b i t g r o w t h of WC p a r t i c l e s in WC-Ni a n d r e s u l t e d in a u n i f o r m g r a i n size. T h e SiC is a l s o reported to s u p p r e s s pore f o r m a t i o n a n d f o r m a t i o n of 0 p h a s e (WaNi3C) w h i c h r e s u l t s in r e d u c e d t r a n s v e r s e r u p t u r e strength.
LITERATURE
REVIEW
No 6, 1993, 28-34. Recent progress in research and d e v e l o p m e n t of i n t e r m e t a l l i c m a t e r i a l s , silicides, saluminides, berylides and c h r o m i d e s is r e v i e w e d . M u c h of t h e work h a s concerned t h e a l u m i n i d e s of Ni, Ti a n d Fe b u t h a s been e x t e n d e d to o t h e r systems including Co, V, Cr Mo a n d W. Properties of selected intermetallics are summarized. LASER P R O C E S S E D TITANIUM ALUMINIDE B A S E D INTERMETALLICS
Y. Ma et al (University of Oslo, Oslo, Norway) J. Materials Research, Vol 7, No 7, 1992, 1722-1734. The use of l a s e r h e a t i n g to synthesize TiAl3, with a d d i t i o n s of Fe, Mn or Cu, is described. Structures a n d c o m p o s i t i o n s of t h e p h a s e s p r e s e n t were determined. The m a t r i x p h a s e was identified as L12. The second p h a s e s t r u c t u r e in t h e alloys with Fe or Ni is r e p o r t e d to b e Fm3m. Lattice p a r a m e t e r m e a s u r e m e n t s are s h o w n to i n d i c a t e a n d a t o m i c size effect in t h e f o r m a t i o n of intermetallics. PREPARATION OF IRON-TITANIUM NITRIDE POWDERS AND SHOCK CONSOLIDATION
T. Yamasaki et al (Himeji Inst. of Technology, Him eji, J a p a n ) , J. Japan Soc. Powder and Powder Metallurgy, Vol 49, No 3, 1993, 324-327. (In J a p a n e s e ) . Mechanical alloying was used to process Fe- (25, 50 or 75)at%Ti powders in N w h i c h were t h e n d y n a m i c a l l y c o m p a c t e d . The powders are shown to consist of ccFe a n d TiN with a grain size of 4 to 7 nm. The Vicker's hardness of the compacted m a t e r i a l is r e p o r t e d to be 1300. After a n n e a l i n g a t 800 °C for 5 h o u r s t h e h a r d n e s s was 1600. A n n e a l i n g at 900°C caused grain growth a n d d i m i n u t i o n in hardness.
Intermetallic Materials FABRICATION OF NICKEL ALUMINIDE BY COMBUSTION SYNTHESIS
I-J. Shon, M-I~ You ( C h o n b u k National University, C h o n b u k , Korea), J. Korean Inst. of Metals, Vol 31, No 3, 1993, 340344. (In Korean). T h e effect of h e a t i n g r a t e o n t h e c o m b u s t i o n synthesis of NizA1, from Ni25at%Al powders, was i n v e s t i g a t e d . A t l°C.min c o m b u s t i o n did n o t occur a n d c o n s t a n t ignition t e m p e r a t u r e was f o u n d for r a t e s of 2 t o 6 0 ° C / m i n . I g n i t i o n temperature increased with further increases in heating rate. The phase composition of t h e p r o d u c t s is described. Below 10°C/min NiAl3,Ni2Al3a n d NiaA1 are formed w i t h residual Ni a n d A1. Above t h i s rate NI3A1 is t h e d o m i n a n t phase. O R D E R E D INTERMETALLIC ALLOYS
I~S. Kumar, C.T. IAu J. Metals, Vol 45,
60 MPR May 1994
PREPARATION OF S I N T E R E D IRON SILICIDE FROM MECHANICALLY GROUND POWDERS
H. Nagai et al (Osaka University, Osaka, J a p a n ) , J. Japan Soc. Powder and Powder Metallurgy, Vol 40, No 3, 1993, 332-336. (In J a p a n e s e ) . An alloy of Fe a n d Si was reduced to p o w d e r by vibratory milling a n d t h e p o w d e r was hot pressed. The milled powder c o n t a i n e d c~Fe2Si5 a n d eFeSi p h a s e s w h i c h d e c o m p o s e d t o 13FeSi2 o n p r o l o n g e d milling. Samples h o t pressed at l l 0 0 ° C a n d 25 MPa for 30 mins a n d h e a t t r e a t e d a t 800°C c o n t a i n e d 13FeSi2 a n d s m a l l a m o u n t s o f ~ p h a s e i r r e s p e c t i v e of t h e c o m p o s i t i o n of t h e p o w d e r . It is shown that prolonged milling and consolidation by h o t pressing gave similar results to s h o r t e r milling t i m e s followed by hot pressing with heat treatment both giving alloys with a high p r o p o r t i o n of ~FeSi2.
Mechanical alloying PHASE TRANSFORMATIONS IN MECHANICALLY ALLOYED NIOBIUMGOLD AND METASTABLE P H A S E S
L.M. D i e t al (University of A m s t e r d a m , A m s t e r d a m , The N e t h e r l a n d s ) Acta Metall. Mater., Vol 41, No 10, 1993, 2923-2932. A study of ball milled Nb-Au p o w d e r is described. Analysis of energy levels is shown to indicate t h a t t h e solid solution h a s a lower e n t h a l p y t h a n t h e a m o r p h o u s state. For five compositions, milled for 40 h o u r s each, differing s t r u c t u r e s are r e p o r t e d . Solid s o l u t i o n s w e r e f o u n d t o follow Vegard's law. The e x o t h e r m i c h e a t of t h e phase restoration is s h o w n t o b e p r o p o r t i o n a l to t h e enthalpy. Powder sizes a n d s h a p e s a n d t h e effects of e x t e n d e d milling were examined. E F F E C T OF A M B I E N T T E M P E R A T U R E ON MECHANICAL ALLOYING IN COPPER-TANTALUM ALLOYS
C-H. Lee et al (Nagoya University, Nagoya, J a p a n ) , J. Korean Inst. of Metals, Vol 31, No 2, 1993, 193-200. (In English). An investigation of a m o r p h i z a t i o n , by m e c h a n i c a l alloying of T a - 3 0 a t % C u is d e s c r i b e d . I t is r e p o r t e d t h a t a f t e r 30 h o u r s grain size is reduced to 100A w i t h o u t a m o r p h i z a t i o n . Thermally assisted a m o r p h i z a t i o n was n o t e d after 60 h o u r s a n d increased t e m p e r a t u r e e n h a n c e d t h e a m o r p h i z a t i o n process. A m o r p h i z a t i o n was also noted on annealing the milled powders. The s t r u c t u r e is s h o w n to be Cu particles in a Ta matrix. E F F E C T S OF MILLING CONDITIONS ON PARTICLE SIZES IN MECHANICALLY ALLOYED POWDERS
L. Gousian et al PM Technology, Vol 11, No 1, 1993, 28-32. (In Chinese). Relationships between energy consumption, process conditions and particle size and morphology, in m e c h a n i c a l alloying were determined. It is s h o w n t h a t , initially, t h e faster t h e r o t a t i o n of t h e mill t h e larger will be t h e particle size. I n l a t e r s t a g e s t h e p a r t i c l e size decreases with t h e increase in energy input. STRUCTURE AND THERMODYNAMIC P R O P E R T I E S OF NANOCRYSTALLINE FACE C E N T R E D CUBIC METALS P R E P A R E D BY MECHANICAL ALLOYING
J. Eckert et al (California Inst. of Technology, Pasadena, California, USA), J. MaterialsResearch, Vol 7, No 7, 1992, 1751-1761. An investigation of s t r u c t u r a l evolution in face c e n t r e d c u b i c m e t a l s d u r i n g mechanical attrition is d e s c r i b e d . Deformation reduced grain size to 6 to 22 n m for different metals. The final grain size is related to melting p o i n t a n d bulk
H. Kolaska, P e t t m a y e r , ( K r u p p W i d i a GmbH, Essen, Germany), MetaU., Vol 47, No 10, 1993, 908-914. (In G e r m a n ) . An historical review of t h e d e v e l o p m e n t of h a r d metal, for cutting tools a n d wear r e s i s t a n t applications, is presented. It is shown t h a t m o d e r n t r e n d s are towards g r e a t e r h o m o g e n e i t y a n d to i m p r o v e d optimization of processes a n d products. Ultrafine grain h a r d m e t a l s a n d cermets a r e a n n o t a t e d a n d t r e n d s in c o a t i n g technology are outlined in t h e light of t h e changes in m a n u f a c t u r i n g technology. A STUDY OF THE SINTERING BEHAVIOUR OF T U N G S T E N CARBIDENICKEL CARBIDE
H-Y. Lee, W-K. Park, ( I n H a University, Incheon, Korea), J. Korean Inst. of Metals, Vol 31, No 2, 1993, 201-207. (In Korean). The effects of applying a SiC coating to WC powder, in a n a t t e m p t to replace Co in WC c e m e n t e d c a r b i d e s b y Ni, w e r e investigated. Density, m i c r o s t r u c t u r e a n d p o r e d i s t r i b u t i o n w e r e d e t e r m i n e d as functions of t h e a m o u n t of SiC added. SiC is r e p o r t e d to i n h i b i t g r o w t h of WC p a r t i c l e s in WC-Ni a n d r e s u l t e d in a u n i f o r m g r a i n size. T h e SiC is a l s o reported to s u p p r e s s pore f o r m a t i o n a n d f o r m a t i o n of 0 p h a s e (WaNi3C) w h i c h r e s u l t s in r e d u c e d t r a n s v e r s e r u p t u r e strength.
LITERATURE
REVIEW
No 6, 1993, 28-34. Recent progress in research and d e v e l o p m e n t of i n t e r m e t a l l i c m a t e r i a l s , silicides, saluminides, berylides and c h r o m i d e s is r e v i e w e d . M u c h of t h e work h a s concerned t h e a l u m i n i d e s of Ni, Ti a n d Fe b u t h a s been e x t e n d e d to o t h e r systems including Co, V, Cr Mo a n d W. Properties of selected intermetallics are summarized. LASER P R O C E S S E D TITANIUM ALUMINIDE B A S E D INTERMETALLICS
Y. Ma et al (University of Oslo, Oslo, Norway) J. Materials Research, Vol 7, No 7, 1992, 1722-1734. The use of l a s e r h e a t i n g to synthesize TiAl3, with a d d i t i o n s of Fe, Mn or Cu, is described. Structures a n d c o m p o s i t i o n s of t h e p h a s e s p r e s e n t were determined. The m a t r i x p h a s e was identified as L12. The second p h a s e s t r u c t u r e in t h e alloys with Fe or Ni is r e p o r t e d to b e Fm3m. Lattice p a r a m e t e r m e a s u r e m e n t s are s h o w n to i n d i c a t e a n d a t o m i c size effect in t h e f o r m a t i o n of intermetallics. PREPARATION OF IRON-TITANIUM NITRIDE POWDERS AND SHOCK CONSOLIDATION
T. Yamasaki et al (Himeji Inst. of Technology, Him eji, J a p a n ) , J. Japan Soc. Powder and Powder Metallurgy, Vol 49, No 3, 1993, 324-327. (In J a p a n e s e ) . Mechanical alloying was used to process Fe- (25, 50 or 75)at%Ti powders in N w h i c h were t h e n d y n a m i c a l l y c o m p a c t e d . The powders are shown to consist of ccFe a n d TiN with a grain size of 4 to 7 nm. The Vicker's hardness of the compacted m a t e r i a l is r e p o r t e d to be 1300. After a n n e a l i n g a t 800 °C for 5 h o u r s t h e h a r d n e s s was 1600. A n n e a l i n g at 900°C caused grain growth a n d d i m i n u t i o n in hardness.
Intermetallic Materials FABRICATION OF NICKEL ALUMINIDE BY COMBUSTION SYNTHESIS
I-J. Shon, M-I~ You ( C h o n b u k National University, C h o n b u k , Korea), J. Korean Inst. of Metals, Vol 31, No 3, 1993, 340344. (In Korean). T h e effect of h e a t i n g r a t e o n t h e c o m b u s t i o n synthesis of NizA1, from Ni25at%Al powders, was i n v e s t i g a t e d . A t l°C.min c o m b u s t i o n did n o t occur a n d c o n s t a n t ignition t e m p e r a t u r e was f o u n d for r a t e s of 2 t o 6 0 ° C / m i n . I g n i t i o n temperature increased with further increases in heating rate. The phase composition of t h e p r o d u c t s is described. Below 10°C/min NiAl3,Ni2Al3a n d NiaA1 are formed w i t h residual Ni a n d A1. Above t h i s rate NI3A1 is t h e d o m i n a n t phase. O R D E R E D INTERMETALLIC ALLOYS
I~S. Kumar, C.T. IAu J. Metals, Vol 45,
60 MPR May 1994
PREPARATION OF S I N T E R E D IRON SILICIDE FROM MECHANICALLY GROUND POWDERS
H. Nagai et al (Osaka University, Osaka, J a p a n ) , J. Japan Soc. Powder and Powder Metallurgy, Vol 40, No 3, 1993, 332-336. (In J a p a n e s e ) . An alloy of Fe a n d Si was reduced to p o w d e r by vibratory milling a n d t h e p o w d e r was hot pressed. The milled powder c o n t a i n e d c~Fe2Si5 a n d eFeSi p h a s e s w h i c h d e c o m p o s e d t o 13FeSi2 o n p r o l o n g e d milling. Samples h o t pressed at l l 0 0 ° C a n d 25 MPa for 30 mins a n d h e a t t r e a t e d a t 800°C c o n t a i n e d 13FeSi2 a n d s m a l l a m o u n t s o f ~ p h a s e i r r e s p e c t i v e of t h e c o m p o s i t i o n of t h e p o w d e r . It is shown that prolonged milling and consolidation by h o t pressing gave similar results to s h o r t e r milling t i m e s followed by hot pressing with heat treatment both giving alloys with a high p r o p o r t i o n of ~FeSi2.
Mechanical alloying PHASE TRANSFORMATIONS IN MECHANICALLY ALLOYED NIOBIUMGOLD AND METASTABLE P H A S E S
L.M. D i e t al (University of A m s t e r d a m , A m s t e r d a m , The N e t h e r l a n d s ) Acta Metall. Mater., Vol 41, No 10, 1993, 2923-2932. A study of ball milled Nb-Au p o w d e r is described. Analysis of energy levels is shown to indicate t h a t t h e solid solution h a s a lower e n t h a l p y t h a n t h e a m o r p h o u s state. For five compositions, milled for 40 h o u r s each, differing s t r u c t u r e s are r e p o r t e d . Solid s o l u t i o n s w e r e f o u n d t o follow Vegard's law. The e x o t h e r m i c h e a t of t h e phase restoration is s h o w n t o b e p r o p o r t i o n a l to t h e enthalpy. Powder sizes a n d s h a p e s a n d t h e effects of e x t e n d e d milling were examined. E F F E C T OF A M B I E N T T E M P E R A T U R E ON MECHANICAL ALLOYING IN COPPER-TANTALUM ALLOYS
C-H. Lee et al (Nagoya University, Nagoya, J a p a n ) , J. Korean Inst. of Metals, Vol 31, No 2, 1993, 193-200. (In English). An investigation of a m o r p h i z a t i o n , by m e c h a n i c a l alloying of T a - 3 0 a t % C u is d e s c r i b e d . I t is r e p o r t e d t h a t a f t e r 30 h o u r s grain size is reduced to 100A w i t h o u t a m o r p h i z a t i o n . Thermally assisted a m o r p h i z a t i o n was n o t e d after 60 h o u r s a n d increased t e m p e r a t u r e e n h a n c e d t h e a m o r p h i z a t i o n process. A m o r p h i z a t i o n was also noted on annealing the milled powders. The s t r u c t u r e is s h o w n to be Cu particles in a Ta matrix. E F F E C T S OF MILLING CONDITIONS ON PARTICLE SIZES IN MECHANICALLY ALLOYED POWDERS
L. Gousian et al PM Technology, Vol 11, No 1, 1993, 28-32. (In Chinese). Relationships between energy consumption, process conditions and particle size and morphology, in m e c h a n i c a l alloying were determined. It is s h o w n t h a t , initially, t h e faster t h e r o t a t i o n of t h e mill t h e larger will be t h e particle size. I n l a t e r s t a g e s t h e p a r t i c l e size decreases with t h e increase in energy input. STRUCTURE AND THERMODYNAMIC P R O P E R T I E S OF NANOCRYSTALLINE FACE C E N T R E D CUBIC METALS P R E P A R E D BY MECHANICAL ALLOYING
J. Eckert et al (California Inst. of Technology, Pasadena, California, USA), J. MaterialsResearch, Vol 7, No 7, 1992, 1751-1761. An investigation of s t r u c t u r a l evolution in face c e n t r e d c u b i c m e t a l s d u r i n g mechanical attrition is d e s c r i b e d . Deformation reduced grain size to 6 to 22 n m for different metals. The final grain size is related to melting p o i n t a n d bulk