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J. Japan soc. powder and powder metallurgy
Science, Vol 40, No 454, 1991, 856-862 (in Japanese). It was reported t h a t 17-4PH stainless steel h a d been p r o d u c e d by MIM a n d sintering. Pore size a n d s h a p e was found to be finer a n d more spherical t h a n was t h e case with an 18-8 stainless. A lower solution t r e a t m e n t t e m p e r a t u r e , 910°C, is reported t h a n for wrought 17-4PH. Age h a r d e n i n g response was said to be t h e same a n d mechanical properties slightly lower.
The structures of splat cooled Mn-Al a n d Mn-A1-Si alloy particles were d e t e r m i n e d by X-ray diffraction. It is reported t h a t only a low t e m p e r a t u r e solid solution was formed in ~Mn (A1,Si) a n d t h a t solid solubility was e x t e n d e d to 10%Mn a n d 20%Si. A n u m b e r of t e r n a r y solid s o l u t i o n s a r e d e s c r i b e d including Mn5(A1,Si)s with some ranges of a m o r p h o u s materials.
Nickel m
STRUCTURAL LOW ALLOY S T E E L S MADE FROM ATOMIZED POWDERS V.N. Klimenko et al (Academy of Sciences of U k r a i n e , Kiev, U k r a i n e ) Poroshkovaya Metallurgiya, No 12, 1991, 4 0 - 4 5 (in Russian). The properties of a range of sintered steels are p r e s e n t e d a n d discussed. The a d v a n t a g e s arising from t h e use of oil atomized powders are outlined.
P R O D U C T I O N OF COLD F O R M E D M E D I U M A N D HIGH ALLOY STEEL PREFORMS S.C. E h l e r t et al, Metals International, Vol 3, No 8, 1990, 26-31. An alternative route for t h e p r o d u c t i o n of high density m e d i u m a n d high alloy steel p a r t s is d e s c r i b e d a n d discussed. The p r o c e d u r e i n c o r p o r a t e s a cold forming s t e p w h i c h r e s u l t s in a r e d u c t i o n in porosity. The m i c r o s t r u c t u r e is shown to have improved compositional homogeneity a n d with spheroidization of pores.
E F F E C T OF MIXING AND PULVERIZING OF NICKEL BASE ALLOY POWDERS USING A STIRRER TYPE MILL S. Takahsai et al (IwakiMeisei University, J a p a n ) , J. Materials Science Letters, Vol 11, No 3, 1992, 173-175. The effects of milling time on grain size, particle s h a p e a n d compositional changes in Ni powders with Mo, Cr, Co a n d TiC were investigated. Stainless steel or HastelloyC were used for mill components. Ni c o n t e n t of t h e p o w d e r in r e p o r t e d to increase slightly with milling time up to 30 h o u r s a n d t h e n to decrease, Ti, Mo, Co a n d C c o n t e n t s were shown to decrease a n d Cr to increase. The s t a r t i n g p o w d e r did n o t contain Fe which was found to increase due to c o n t a m i n a t i o n from t h e mill parts. Particle size was reduced to a m i n i m u m of 0.5 to 1.0 p m a n d was uniform after 90 h o u r s milling.
L. Dongchun et al (Yanshan University, Qinuangdo of Hebei, China), PM Technology, Vol 10, No 3, 1992, 204-208, (in Chinese). The p a p e r describes a s t u d y of t h e effects of additions of Cu a n d Ni on t h e sintering of s h o r t CI fibres at l l 0 0 ° C . E x p a n s i o n is r e p o r t e d to be reduced by Cu due to t h e formation of a liquid phase. Densification is e n h a n c e d by a d d i t i o n of Ni. Austenite in the m i c r o s t r u c t u r e at Ni above 4.5%. The s t r u c t u r e s of t h e alloys are described.
Manganese AN X-RAY INVESTIGATION OF MANGANESE ALLOYS WITH ALUMINIUM AND SILICON M. Ellner, T. RShrer (Max Planck Inst., S t u t t g a r t , G e r m a n y ) Z. Metallkunde, Vol 82, No 10, 1991, 799-804, (in German).
40 MPR February 1993
ANALYSIS OF HIGH T E M P E R A T U R E C R E E P IN PM T U N G S T E N WIRES K. Tanoue et al (Kyushi Inst. of Technology, Kitakyushi, J a p a n ) J. Japan Soc. Powder and Powder Metallurgy, Vol 39, No 3, 1992, 168-173 (in J a p a n e s e ) . An analysis of t h e high t e m p e r a t u r e creep of PM W wire is described. The analysis was by a (} projection m e t h o d b a s e d o n e x h a u s t i o n t h e o r y of active dislocations. Grain b o u n d a r y sliding a n d o t h e r m e c h a n i s m s are t a k e n into account a n d it is shown to be possible to derive a creep cure for a n arbitrary temperature.
Ceramics P R O C E S S I N G OF ADVANCED CERAMIC POWDERS J. B i n n e r (University of Nottingham, England, UK), Metals and Materials, Vol 8, No 10, 1992, 534-537. The applications of structural, electronic ceramic a n d ceramic coatings are reviewed. Process m e t h o d s making use of powders are discussed with reference to solid state, solution based and vapour phase technologies. The economic p o t e n t i a l of advanced ceramics is outlined with regard to future m a r k e t prospects. ANALYSIS OF S I N T E R I N G IN P R E S E N C E OF H E T E R O G E N E I T I E S
Titanium E F F E C T S OF COPPER AND NICKEL ON SINTERING CHARACTERIZATION OF SHORT CAST IRON ( C I ) F I B R E S
Tungsten
FAILURE M E C H A N I S M S IN POROUS TITANIUM D U R I N G FATIGUE FAILURE E. Bobrova Pokroky Psaskove Metalurgie, No 3-4, 1991, 59-67 (in Czech) A study of fatigue fractures in PM Ti6.5%Al-3.2%Mo-l.5%Zr-0.25%Si, with a n ¢t/~ m a r t e n s i t i c structure, is reported. Fatigue m e c h a n i s m s leading to failure are derived.
E F F E C T OF HEAT T R E A T M E N T ON MICROSTRUCTURE OF TITANIUMALUMINIUM ALLOY MADE FROM ELEMENTAL POWDERS G-X. Wang, M. D a h m s (GKSS Research Centre, Germany), Scripta Metall. Mater., Vol 26, No 5, 1992, 717-722. Ti-35%A1, n e a r T structure, specimens were p r e p a r e d from elemental powders a n d the properties a n d s t r u c t u r e s d e t e r m i n e d before a n d after HIP a n d h e a t t r e a t m e n t which was required to a t t a i n homogeneity. Grain size, oxidation a n d partial melting are noted. A range of dual p h a s e s t r u c t u r e s are reported depending on process conditions.
S.J. Kiss, E. Kostic (Inst. for N u c l e a r Sciences, Belgrade, Yugoslavia), Powder Metall. Int., Vol 24, No 4, 1992, 247-250. A study of t h e sintering of A12Oa, with a n d w i t h o u t a liquid p h a s e a n d in presence of n o n - s i n t e r a b l e inclusions is described. A12O3-SiO2 composites, with pellets of fully d e n s e A1203 w e r e i n v e s t i g a t e d . T h e inhibition of sintering by SiO2 is noted w i t h d e v e l o p m e n t of i n t e r n a l stresses. Anisotropic shrinkage is m o d e l l e d . Additives giving liquid p h a s e are reported to enable t h e formation of h o m o g e n e o u s microstructures. WETTING OF CERAMIC MATERIALS WITH MOLTEN METALS H. H a u s n e r (Technical University, Berlin, Germany) PM Science and Technology, Vol 3, No 3 1992, 25-33. The wetting of ceramic m a t e r i a l s by m o l t e n m e t a l s is d i s c u s s e d a n d t h e i m p o r t a n c e of g o o d w e t t i n g in, f o r example, joining, is emphasized. Interface energies between p h a s e s form the basis of wetting behaviour and these are s u m m a r i z e d w i t h p o s s i b l e e f f e c t s of interaction between phases. Factors influencing wetting including surface
The structures of splat cooled Mn-Al a n d Mn-A1-Si alloy particles were d e t e r m i n e d by X-ray diffraction. It is reported t h a t only a low t e m p e r a t u r e solid solution was formed in ~Mn (A1,Si) a n d t h a t solid solubility was e x t e n d e d to 10%Mn a n d 20%Si. A n u m b e r of t e r n a r y solid s o l u t i o n s a r e d e s c r i b e d including Mn5(A1,Si)s with some ranges of a m o r p h o u s materials.
Nickel m
STRUCTURAL LOW ALLOY S T E E L S MADE FROM ATOMIZED POWDERS V.N. Klimenko et al (Academy of Sciences of U k r a i n e , Kiev, U k r a i n e ) Poroshkovaya Metallurgiya, No 12, 1991, 4 0 - 4 5 (in Russian). The properties of a range of sintered steels are p r e s e n t e d a n d discussed. The a d v a n t a g e s arising from t h e use of oil atomized powders are outlined.
P R O D U C T I O N OF COLD F O R M E D M E D I U M A N D HIGH ALLOY STEEL PREFORMS S.C. E h l e r t et al, Metals International, Vol 3, No 8, 1990, 26-31. An alternative route for t h e p r o d u c t i o n of high density m e d i u m a n d high alloy steel p a r t s is d e s c r i b e d a n d discussed. The p r o c e d u r e i n c o r p o r a t e s a cold forming s t e p w h i c h r e s u l t s in a r e d u c t i o n in porosity. The m i c r o s t r u c t u r e is shown to have improved compositional homogeneity a n d with spheroidization of pores.
E F F E C T OF MIXING AND PULVERIZING OF NICKEL BASE ALLOY POWDERS USING A STIRRER TYPE MILL S. Takahsai et al (IwakiMeisei University, J a p a n ) , J. Materials Science Letters, Vol 11, No 3, 1992, 173-175. The effects of milling time on grain size, particle s h a p e a n d compositional changes in Ni powders with Mo, Cr, Co a n d TiC were investigated. Stainless steel or HastelloyC were used for mill components. Ni c o n t e n t of t h e p o w d e r in r e p o r t e d to increase slightly with milling time up to 30 h o u r s a n d t h e n to decrease, Ti, Mo, Co a n d C c o n t e n t s were shown to decrease a n d Cr to increase. The s t a r t i n g p o w d e r did n o t contain Fe which was found to increase due to c o n t a m i n a t i o n from t h e mill parts. Particle size was reduced to a m i n i m u m of 0.5 to 1.0 p m a n d was uniform after 90 h o u r s milling.
L. Dongchun et al (Yanshan University, Qinuangdo of Hebei, China), PM Technology, Vol 10, No 3, 1992, 204-208, (in Chinese). The p a p e r describes a s t u d y of t h e effects of additions of Cu a n d Ni on t h e sintering of s h o r t CI fibres at l l 0 0 ° C . E x p a n s i o n is r e p o r t e d to be reduced by Cu due to t h e formation of a liquid phase. Densification is e n h a n c e d by a d d i t i o n of Ni. Austenite in the m i c r o s t r u c t u r e at Ni above 4.5%. The s t r u c t u r e s of t h e alloys are described.
Manganese AN X-RAY INVESTIGATION OF MANGANESE ALLOYS WITH ALUMINIUM AND SILICON M. Ellner, T. RShrer (Max Planck Inst., S t u t t g a r t , G e r m a n y ) Z. Metallkunde, Vol 82, No 10, 1991, 799-804, (in German).
40 MPR February 1993
ANALYSIS OF HIGH T E M P E R A T U R E C R E E P IN PM T U N G S T E N WIRES K. Tanoue et al (Kyushi Inst. of Technology, Kitakyushi, J a p a n ) J. Japan Soc. Powder and Powder Metallurgy, Vol 39, No 3, 1992, 168-173 (in J a p a n e s e ) . An analysis of t h e high t e m p e r a t u r e creep of PM W wire is described. The analysis was by a (} projection m e t h o d b a s e d o n e x h a u s t i o n t h e o r y of active dislocations. Grain b o u n d a r y sliding a n d o t h e r m e c h a n i s m s are t a k e n into account a n d it is shown to be possible to derive a creep cure for a n arbitrary temperature.
Ceramics P R O C E S S I N G OF ADVANCED CERAMIC POWDERS J. B i n n e r (University of Nottingham, England, UK), Metals and Materials, Vol 8, No 10, 1992, 534-537. The applications of structural, electronic ceramic a n d ceramic coatings are reviewed. Process m e t h o d s making use of powders are discussed with reference to solid state, solution based and vapour phase technologies. The economic p o t e n t i a l of advanced ceramics is outlined with regard to future m a r k e t prospects. ANALYSIS OF S I N T E R I N G IN P R E S E N C E OF H E T E R O G E N E I T I E S
Titanium E F F E C T S OF COPPER AND NICKEL ON SINTERING CHARACTERIZATION OF SHORT CAST IRON ( C I ) F I B R E S
Tungsten
FAILURE M E C H A N I S M S IN POROUS TITANIUM D U R I N G FATIGUE FAILURE E. Bobrova Pokroky Psaskove Metalurgie, No 3-4, 1991, 59-67 (in Czech) A study of fatigue fractures in PM Ti6.5%Al-3.2%Mo-l.5%Zr-0.25%Si, with a n ¢t/~ m a r t e n s i t i c structure, is reported. Fatigue m e c h a n i s m s leading to failure are derived.
E F F E C T OF HEAT T R E A T M E N T ON MICROSTRUCTURE OF TITANIUMALUMINIUM ALLOY MADE FROM ELEMENTAL POWDERS G-X. Wang, M. D a h m s (GKSS Research Centre, Germany), Scripta Metall. Mater., Vol 26, No 5, 1992, 717-722. Ti-35%A1, n e a r T structure, specimens were p r e p a r e d from elemental powders a n d the properties a n d s t r u c t u r e s d e t e r m i n e d before a n d after HIP a n d h e a t t r e a t m e n t which was required to a t t a i n homogeneity. Grain size, oxidation a n d partial melting are noted. A range of dual p h a s e s t r u c t u r e s are reported depending on process conditions.
S.J. Kiss, E. Kostic (Inst. for N u c l e a r Sciences, Belgrade, Yugoslavia), Powder Metall. Int., Vol 24, No 4, 1992, 247-250. A study of t h e sintering of A12Oa, with a n d w i t h o u t a liquid p h a s e a n d in presence of n o n - s i n t e r a b l e inclusions is described. A12O3-SiO2 composites, with pellets of fully d e n s e A1203 w e r e i n v e s t i g a t e d . T h e inhibition of sintering by SiO2 is noted w i t h d e v e l o p m e n t of i n t e r n a l stresses. Anisotropic shrinkage is m o d e l l e d . Additives giving liquid p h a s e are reported to enable t h e formation of h o m o g e n e o u s microstructures. WETTING OF CERAMIC MATERIALS WITH MOLTEN METALS H. H a u s n e r (Technical University, Berlin, Germany) PM Science and Technology, Vol 3, No 3 1992, 25-33. The wetting of ceramic m a t e r i a l s by m o l t e n m e t a l s is d i s c u s s e d a n d t h e i m p o r t a n c e of g o o d w e t t i n g in, f o r example, joining, is emphasized. Interface energies between p h a s e s form the basis of wetting behaviour and these are s u m m a r i z e d w i t h p o s s i b l e e f f e c t s of interaction between phases. Factors influencing wetting including surface