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Ostwald ripening and coalescence liquid phase sintered copper-cobalt alloys
PM
Powder Metallurgy, Vol 35, No 2, 1992, 133136. Composite 6061A1 alloys were m a d e by blending alloy powders with ~/A1203 fibres, h o t e x t r u s i o n a n d h e a t t r e a t m e n t to T6 condition. Densities of q7.5 a n d 99.3% were o b t a i n e d with composites c o n t a i n i n g 30 or 10 vol% fibre respectively. The highest a n d lowest ambient temperature tensile s t r e n g t h s are r e p o r t e d for t h e specimens with 15 a n d 30% ductility being reduced as t h e fibre c o n t e n t increased. Properties are reduced by increased temperatures. Bend strength is a maximum a t 15% reinforcement. C R E E P FRACTURE OF ALUMINIUM CARBIDE D I S P E R S I O N S T R E N G T H E N E D ALUMINIUM
G. J a n g g et al, ( T e c h n i c a l University, V i e n n a , A u s t r i a ) , Z Ffir M e t a l l k u n d e , Vol 83, No 3, 1992, 183-189. (In G e r m a n ) . Rupture b e h a v i o u r of AI-5 vol% A14C3 is described w i t h respect to creep. Creep mechanisms, predominantly dislocation climb, proceed simultaneously resulting in small elongations to fracture a t low creep tensile stresses. At high creep s t r e s s e s polygonization leads to increased e l o n g a t i o n to f r a c t u r e . D i f f e r e n c e s in compressive a n d tensile yield s t r e n g t h s are a t t r i b u t e d to g r a i n b o u n d a r y debonding.
Copper OSTWALD RIPENING AND COALESCENCE LIQUID PHASE S I N T E R E D COPPER-COBALT ALLOYS
W. Bender a n d L. Ratke, (Inst ftir Raumsimulation, KSln, Germany), Z ffir Metallkunde, Vol 83, No 7, 1992, 541-547. (In G e r m a n ) . LPS of Cu-(30 to 50 vol% Co) was investigated a n d t h e results are discussed in t e r m s of the theory of Ostwald ripening. Good a g r e e m e n t between predicted a n d e x p e r i m e n t a l r e s u l t s is reported. There were some discrepancies at long h e a t i n g times a n d these are discussed in t e r m s of agglomeration of Co particles. E F F E C T S OF A D D I T I O N S OF LEAD AND CALCIUM FLUORIDE ON STRUCTURE AND TRIBOLGICAL P R O P E R T I E S OF PM COPPER-BASE MATERIALS
LITERATURE
REVIEW
e x h u d a t i o n of Pb. Pb reduced friction a n d at 11% Pb increases wear rate. E F F E C T S OF POWDER D I S P E R S I O N ON COMPACTION OF BRASS POWDERS
V.S. K r u z h a n o v a n d T.G. G a r b o v i t s k y a , Poroshkovaya Metallugiya, No 9, 1991, 59. (In Russian). A study of h o t c o m p a c t i o n of Cu a n d brass powders is described. It is shown t h a t n e a r pore free b r a s s can be p r o d u c e d from 10 p m powder by pressing a t 650 to 700°C a n d 120 to 150 MPa for 3 to 5 minutes. Homogenization is limited by diffusion of Zn in Cu or brass. Compaction t e m p e r a t u r e s can be reduced by use of m o r e d i s p e r s e d p o w d e r or Cu c o a t e d powders w i t h o u t loss of quality. USE OF MECHANICAL ALLOYING IN DEVELOPMENT OF OXIDE AND CARBIDE D I S P E R S I O N STRENGTHENED COPPERS
T. Takahashi, (Inst of Industrial Research, Hyogo, Kyoto, J a p a n ) , J Japan Soc Powder and Powder Metallurgy, Vol 39, No 7, 1992, 529-238. (In J a p a n e s e ) . An investigation in which MA was used to p r e p a r e oxide a n d carbide s t r e n g t h e n e d Cu specimens is described. It is s h o w n t h a t t h e oxides used do not result in increase in s t r e n g t h because of oxide particle growth a n d s e p a r a t i o n of Cu f r o m t h e alloy powders during heating. In t h e case of t h e carbide reinforced materials increased t h e r m a l stability is n o t e d a n d s t r e n g t h s of 650 to 725 MPa are reported. Cu-AI-O a n d Cu-Ti-C are included in t h e systems studied. FORMATION OF COPPER-ALUMINA COMPOSITE PARTICLES AND THE E F F E C T OF OXYGEN ON THE P R O C E S S OF MECHANOFUSION
H. Kaga et al, ( I n d u s t r i a l T e c h n o l o g y Centre, Hokkaido, J a p a n ) , J Japan Soc Powder and Powder Metallurgy, Vol 39, No 7, 1992, 553-558. (In J a p a n e s e ) . The use of m e c h a n o f u s i o n to coat Cu particles with A1203 particles is described. The yield of coated powder is higher in Ar or v a c u u m t h a n in air. The p r o c e s s e d particles are r e p o r t e d to be m a r k e d where A1203 f r a g m e n t s have d e t a c h e d from t h e surface of the Cu. It is r e p o r t e d t h a t t h e Cu powders could be completely coated with A1203 if t h e process t i m e was long enough.
Iron and steel e t al, P o r o s h k o v a y a Metallurgiya, No 8, 1991, 78-83. (In Russian). The effects of CaF 2 a n d Pb on t h e s t r u c t u r e a n d t r i b o t e c h n i c a l p r o p e r t i e s of Cu base bearing alloys were investigated. It is shown t h a t the effect of CaF2 is limited to influence of tribological properties, increase in volume s h r i n k a g e a n d p r e v e n t i o n of N.G.
Baranov
WEAR R E S I S T A N T PM S T E E L BY A LOW T E M P E R A T U R E P R O C E S S I N G ROUTE
N. C a r l b a u m a n d P. Engdahl, (H6gan~is, Sweden), Powder Metallurgy, Vol 35, No 2, 1992, 137-139. The d e v e l o p m e n t of a wear r e s i s t a n t
steel, Fe-l%C-0.6%P-10%Mo, is described. The steel is r e p o r t e d to be sintered at 1120°C for 30 m i n u t e s in N. A c o m p a r i s o n is m a d e with M2 high speed steel a n d similar h a r d n e s s a n d wear p r o p e r t i e s are reported. STRUCTURE AND P R O P E R T I E S OF PRECIPITATION H A R D E N E D A U S T E N I T I C PM S T E E L S
O._~ Bannych et al, (Academy of Sciences, Moscow, Russia), Zfiir Metallkunde, Vol 83, No 4, 1992, 236-240. T h e s h a p e a n d d i s t r i b u t i o n of VC particles in h o t e x t r u d e d a n d hot rolled PM high C Mn-Ni-V steels was studied. It is shown t h a t higher t h e values of m e c h a n i c a l p r o p e r t i e s t h a n for conventional steels can be a t t r i b u t e d to t h e finer s t r u c t u r e s of PM steels. MANUFACTURE OF ROLLER BEARING RINGS FROM PREALLOYED NICKEL MOLYBDENUM STEEL POWDERS
A. Shalk, Poroshkovaya Metallurgiya, No 11, 1991, 72-78. (In Russian). Mechanical properties, contact durability a n d wear properties of bearing p a r t s m a d e from Fe-Ni-Mo powders are d e s c r i b e d . It is r e p o r t e d t h a t r i n g c o m p o n e n t s of ball a n d similar bearings have durabilities c o m p a r a b l e with those of conventional bearings steels. E N H A N C E D PERFORMANCE STAINLESS S T E E L
R.G. H a m e r t o n et al, (AEA I n d u s t r i a l Technology, Risley, UK), Materials World, Vol 1, No 1, 1993, 9-10. The d e v e l o p m e n t of a nitride particle s t r e n g t h e n i n g s i n t e r e d austenitic stainless steel is described. It is shown t h a t t h e steel has enhanced wear properties and increased strength. N is i n t r o d u c e d into t h e steel powders e i t h e r by mechanofusion, gas n i t r i d i n g or by c o - s p r a y i n g billets containing nitrides. Possible a p p l i c a t i o n s are considered. SINTERING MECHANISMS IN IRON CONTAINING BORIDE BASE HARD MATERIALS
T. Ide et al, (Toyo Kohan Co Ltd, Kudamatsu, J a p a n ) , J Japan Soc Powder and Powder Metallurgy, Vol 39, No 4, 1992, 247253. (In J a p a n e s e ) . The m i c r o s t r u c t u r e s of Fe-6%B alloys with varying a m o u n t s of Mo are reported to consist of particles of FeMo2B2 in a ferritic matrix. Liquid p h a s e sintering of t h e alloys was investigated h)r alloys p r e p a r e d from Fe, Mo a n d FeB powders a n d FeMo2B 2 forms by reaction. Two liquid p h a s e s are r e p o r t e d which form at 1092°C a n d 1142°C a t which t h e only solid is FeMo2B2. The densification m e c h a n i s m includes solution/ p r e c i p i t a t i o n of FeMo2B 2.
MPR March 1993 51
Powder Metallurgy, Vol 35, No 2, 1992, 133136. Composite 6061A1 alloys were m a d e by blending alloy powders with ~/A1203 fibres, h o t e x t r u s i o n a n d h e a t t r e a t m e n t to T6 condition. Densities of q7.5 a n d 99.3% were o b t a i n e d with composites c o n t a i n i n g 30 or 10 vol% fibre respectively. The highest a n d lowest ambient temperature tensile s t r e n g t h s are r e p o r t e d for t h e specimens with 15 a n d 30% ductility being reduced as t h e fibre c o n t e n t increased. Properties are reduced by increased temperatures. Bend strength is a maximum a t 15% reinforcement. C R E E P FRACTURE OF ALUMINIUM CARBIDE D I S P E R S I O N S T R E N G T H E N E D ALUMINIUM
G. J a n g g et al, ( T e c h n i c a l University, V i e n n a , A u s t r i a ) , Z Ffir M e t a l l k u n d e , Vol 83, No 3, 1992, 183-189. (In G e r m a n ) . Rupture b e h a v i o u r of AI-5 vol% A14C3 is described w i t h respect to creep. Creep mechanisms, predominantly dislocation climb, proceed simultaneously resulting in small elongations to fracture a t low creep tensile stresses. At high creep s t r e s s e s polygonization leads to increased e l o n g a t i o n to f r a c t u r e . D i f f e r e n c e s in compressive a n d tensile yield s t r e n g t h s are a t t r i b u t e d to g r a i n b o u n d a r y debonding.
Copper OSTWALD RIPENING AND COALESCENCE LIQUID PHASE S I N T E R E D COPPER-COBALT ALLOYS
W. Bender a n d L. Ratke, (Inst ftir Raumsimulation, KSln, Germany), Z ffir Metallkunde, Vol 83, No 7, 1992, 541-547. (In G e r m a n ) . LPS of Cu-(30 to 50 vol% Co) was investigated a n d t h e results are discussed in t e r m s of the theory of Ostwald ripening. Good a g r e e m e n t between predicted a n d e x p e r i m e n t a l r e s u l t s is reported. There were some discrepancies at long h e a t i n g times a n d these are discussed in t e r m s of agglomeration of Co particles. E F F E C T S OF A D D I T I O N S OF LEAD AND CALCIUM FLUORIDE ON STRUCTURE AND TRIBOLGICAL P R O P E R T I E S OF PM COPPER-BASE MATERIALS
LITERATURE
REVIEW
e x h u d a t i o n of Pb. Pb reduced friction a n d at 11% Pb increases wear rate. E F F E C T S OF POWDER D I S P E R S I O N ON COMPACTION OF BRASS POWDERS
V.S. K r u z h a n o v a n d T.G. G a r b o v i t s k y a , Poroshkovaya Metallugiya, No 9, 1991, 59. (In Russian). A study of h o t c o m p a c t i o n of Cu a n d brass powders is described. It is shown t h a t n e a r pore free b r a s s can be p r o d u c e d from 10 p m powder by pressing a t 650 to 700°C a n d 120 to 150 MPa for 3 to 5 minutes. Homogenization is limited by diffusion of Zn in Cu or brass. Compaction t e m p e r a t u r e s can be reduced by use of m o r e d i s p e r s e d p o w d e r or Cu c o a t e d powders w i t h o u t loss of quality. USE OF MECHANICAL ALLOYING IN DEVELOPMENT OF OXIDE AND CARBIDE D I S P E R S I O N STRENGTHENED COPPERS
T. Takahashi, (Inst of Industrial Research, Hyogo, Kyoto, J a p a n ) , J Japan Soc Powder and Powder Metallurgy, Vol 39, No 7, 1992, 529-238. (In J a p a n e s e ) . An investigation in which MA was used to p r e p a r e oxide a n d carbide s t r e n g t h e n e d Cu specimens is described. It is s h o w n t h a t t h e oxides used do not result in increase in s t r e n g t h because of oxide particle growth a n d s e p a r a t i o n of Cu f r o m t h e alloy powders during heating. In t h e case of t h e carbide reinforced materials increased t h e r m a l stability is n o t e d a n d s t r e n g t h s of 650 to 725 MPa are reported. Cu-AI-O a n d Cu-Ti-C are included in t h e systems studied. FORMATION OF COPPER-ALUMINA COMPOSITE PARTICLES AND THE E F F E C T OF OXYGEN ON THE P R O C E S S OF MECHANOFUSION
H. Kaga et al, ( I n d u s t r i a l T e c h n o l o g y Centre, Hokkaido, J a p a n ) , J Japan Soc Powder and Powder Metallurgy, Vol 39, No 7, 1992, 553-558. (In J a p a n e s e ) . The use of m e c h a n o f u s i o n to coat Cu particles with A1203 particles is described. The yield of coated powder is higher in Ar or v a c u u m t h a n in air. The p r o c e s s e d particles are r e p o r t e d to be m a r k e d where A1203 f r a g m e n t s have d e t a c h e d from t h e surface of the Cu. It is r e p o r t e d t h a t t h e Cu powders could be completely coated with A1203 if t h e process t i m e was long enough.
Iron and steel e t al, P o r o s h k o v a y a Metallurgiya, No 8, 1991, 78-83. (In Russian). The effects of CaF 2 a n d Pb on t h e s t r u c t u r e a n d t r i b o t e c h n i c a l p r o p e r t i e s of Cu base bearing alloys were investigated. It is shown t h a t the effect of CaF2 is limited to influence of tribological properties, increase in volume s h r i n k a g e a n d p r e v e n t i o n of N.G.
Baranov
WEAR R E S I S T A N T PM S T E E L BY A LOW T E M P E R A T U R E P R O C E S S I N G ROUTE
N. C a r l b a u m a n d P. Engdahl, (H6gan~is, Sweden), Powder Metallurgy, Vol 35, No 2, 1992, 137-139. The d e v e l o p m e n t of a wear r e s i s t a n t
steel, Fe-l%C-0.6%P-10%Mo, is described. The steel is r e p o r t e d to be sintered at 1120°C for 30 m i n u t e s in N. A c o m p a r i s o n is m a d e with M2 high speed steel a n d similar h a r d n e s s a n d wear p r o p e r t i e s are reported. STRUCTURE AND P R O P E R T I E S OF PRECIPITATION H A R D E N E D A U S T E N I T I C PM S T E E L S
O._~ Bannych et al, (Academy of Sciences, Moscow, Russia), Zfiir Metallkunde, Vol 83, No 4, 1992, 236-240. T h e s h a p e a n d d i s t r i b u t i o n of VC particles in h o t e x t r u d e d a n d hot rolled PM high C Mn-Ni-V steels was studied. It is shown t h a t higher t h e values of m e c h a n i c a l p r o p e r t i e s t h a n for conventional steels can be a t t r i b u t e d to t h e finer s t r u c t u r e s of PM steels. MANUFACTURE OF ROLLER BEARING RINGS FROM PREALLOYED NICKEL MOLYBDENUM STEEL POWDERS
A. Shalk, Poroshkovaya Metallurgiya, No 11, 1991, 72-78. (In Russian). Mechanical properties, contact durability a n d wear properties of bearing p a r t s m a d e from Fe-Ni-Mo powders are d e s c r i b e d . It is r e p o r t e d t h a t r i n g c o m p o n e n t s of ball a n d similar bearings have durabilities c o m p a r a b l e with those of conventional bearings steels. E N H A N C E D PERFORMANCE STAINLESS S T E E L
R.G. H a m e r t o n et al, (AEA I n d u s t r i a l Technology, Risley, UK), Materials World, Vol 1, No 1, 1993, 9-10. The d e v e l o p m e n t of a nitride particle s t r e n g t h e n i n g s i n t e r e d austenitic stainless steel is described. It is shown t h a t t h e steel has enhanced wear properties and increased strength. N is i n t r o d u c e d into t h e steel powders e i t h e r by mechanofusion, gas n i t r i d i n g or by c o - s p r a y i n g billets containing nitrides. Possible a p p l i c a t i o n s are considered. SINTERING MECHANISMS IN IRON CONTAINING BORIDE BASE HARD MATERIALS
T. Ide et al, (Toyo Kohan Co Ltd, Kudamatsu, J a p a n ) , J Japan Soc Powder and Powder Metallurgy, Vol 39, No 4, 1992, 247253. (In J a p a n e s e ) . The m i c r o s t r u c t u r e s of Fe-6%B alloys with varying a m o u n t s of Mo are reported to consist of particles of FeMo2B2 in a ferritic matrix. Liquid p h a s e sintering of t h e alloys was investigated h)r alloys p r e p a r e d from Fe, Mo a n d FeB powders a n d FeMo2B 2 forms by reaction. Two liquid p h a s e s are r e p o r t e d which form at 1092°C a n d 1142°C a t which t h e only solid is FeMo2B2. The densification m e c h a n i s m includes solution/ p r e c i p i t a t i o n of FeMo2B 2.
MPR March 1993 51