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Microstructure of ultrafine carbonyl iron powder
Three AI alloys., A1-4%Cr-l%Fe, A1-5%Cr2%Zr a n d A1-6, 43%Cr-1, 67%Zr were fabricated from rapidly solidified powder by cold p r e s s i n g a n d h o t e x t r u s i o n . Decomposition of the powder microstructure and coarsening during thermomechanical treatment was i n v e s t i g a t e d a t t h r e e l o c a t i o n s in t h e partially e x t r u d e d materials. In the dead zone the two low Cr alloys showed rapid decomposition of the powder microstructure due to heating alone but the high Cr alloy was little changed. In t h e deformation zone t h e precipitation kinetics are affected by shearing and t h e internal heating effect due to extrusion. Particles of i n t e r m e t a l l i c s b e c a m e a l i g n e d in t h e d i r e c t i o n of e x t r u s i o n . T h e e x t r u d e d material is reported to be heterogeneous a n d fibrous• PREPARATION OF AN AMORPHOUS ALUMINIUM-NICKEL-YTTRIUM ALLOY POWDER AND BULK MATERIAL
Z-H. Chen et al, (Central South University of Technology, C h i n a ) J Less Common Metals, Vol 171, No 2, 1991, 187-194. It is shown t h a t a m o r p h o u s Al-10at% Y5% Ni alloy powder can be produced by rapid solidification. The characteristics a n d t h e r m a l s t a b i l i t y of t h e p o w d e r a r e discussed. The use of explosive compaction, v a c u u m hot pressing of h o t extrusion are reported to enable consolidation of the powder to amorphous, amorphous and microcrystalline, or microcrystalline bulk material, respectively, a n d the properties are described.
Beryllium MICRO YIELD STRENGTH OF BERYLLIUM CONSOLIDATED BY PM METHODS
B.G. Naik a n d V.IC Singhal, ( B h a b a Atomic Research Centre, Bombay, India), Trans, PMAssoc. of India, Vol 18, 1991, 31-35. The a p p l i c a t i o n s of s i n t e r e d Be are reviewed w i t h r e g a r d to p h y s i c a l a n d mechanical properties. The stability u n d e r stress, which is related to the rigidity, is quantified by micro yield s t r e n g t h (MYS). The d e v e l o p m e n t of a t e c h n i q u e for evaluation of MYS is described a n d t h e factors which influence it are discussed.
33 at% B was mechanically alloyed for 150 h o u r s a n d t h e n e x a m i n e d by X-ray diffraction, X-ray spectroscopy and d i f f e r e n t i a l s c a n n i n g c a l o r i m e t r y . The s t r u c t u r e s are reported to be d e p e n d e n t of t h e filling ratio of t h e mill (charge: void ratio, f:v). For a ratio of 1:1 only partial a m o r p h i z a t i o n is achieved a n d a steady state is reached after 25 h o u r s milling. For more energetic milling a t f:v o f 1:5 a m o r p h i z a t i o n is a l m o s t c o m p l e t e after 70 hours. In t h e final stages t h e f o r m a t i o n of t-Co2B is r e p o r t e d a n d a steady s t a t e exists between crystalline a n d a m o r p h o u s materials.
Copper PROCESS PARAMETERS FOR BONDING COPPER POWDER TO OXYGEN F R E E HIGH CONDUCTIVITY ( O F H C ) COPPER SUBSTRATE BY CIP AND SINTERING
G.~. Rao et al, (Defence Materials Research Laboratory, Hyderabad, India), Trans PM Assoc. of India, Vol 18, 1991, 27-30 The fabrication of a c o m p o n e n t in which Cu powder is b o n d e d to a n OFHC Cu s u b s t r a t e , b y C I P a n d s i n t e r i n g is described. The bond strength was evaluated by m e a n s of a s h e a r test a n d t h e process condition were optimized on t h e basis of t h e d e b o n d i n g test.
SINTERING OF COPPER COMPACTS WITH CHANNELS
V.G. Zatovsky et al, (Academy of Sciences of the ~ne, Kiev, Ukraine), Poroshkovaya Metallurgiya, No 5, 1991, 18-22. (In Russian). An investigation of the sintering of Cu compacts containing channels, which are introduced by t h e addition of fibres which d e c o m p o s e thermally, is described. The shrinkage of t h e c o m p o n e n t is reported to be greater t h a n t h e change in volume of t h e channels. Swelling is noted w h e n the fibres u s e d were b e l o w 0.3 m m a n d t h i s is a t t r i b u t e d to i m p e d e d r e m o v a l of t h e gaseous p r o d u c t s of decomposition of t h e fibres.
Iron and steel
Cobalt SOLID STATE REACTION IN MILLING OF COBALT-BORON POWDER MIXTURES
A. Corrias et al, (University of Cagliari, S a r d i n i a , Italy), J Materials Science, Vol 26, No 18, 1991, 5081-5084. A powder m i x t u r e consisting of Co with
SINTERING OF MOLYBDENUM ALLOYED PM S T E E L S PREPARED FROM ELEMENTAL POWDERS
H. Danninger, (Technical University, Vienna, Austria), Powder Metall. Int., Vol 24, No 2, 1992, 73-79 The p a p e r describes an investigation into the effects of sintering temperatures, in t h e r a n g e 1160 ° to 1360°C, on t h e
mechanical properties of sintered Fe-l.5% Mo-0.7%. It is reported t h a t a t r a n s i e n t liquid p h a s e is formed above 1230°C which results in a more h o m o g e n e o u s distribution o f Mo a n d c o n s e q u e n t l y improved mechanical p r o p e r t i e s of b o t h as-sintered a n d heat t r e a t e d materials. SURFACE DURABILITY OF THROUGHH A R D E N E D PM S T E E L GEARS
C. M a d h a v a n a n d I~ Gopinath, (Institute of Technology, Madras, I n d i a ) , Trans PM Assoe of India, Vol 18, 1991, 37-46. A rig for testing steel, 1.7% Ni-1.5% Cu0.8% Mo-0.5% C, gears is described. Wear is m o n i t o r e d by t o o t h thickness, weight loss, acoustic emission a n d Fe c o n t a m i n a t i o n of t h e oil. The m e c h a n i s m s are mild wear, pitting a n d surface fatigue. A wear rate e q u a t i o n is given a n d g e a r f a i l u r e is analysed. ALLOYING OF IRON POWDER BASE ALLOYS WITH CHROMIUM AND ITS COMPOUNDS
E_A. Mazurenko et al, Poroshkovaya Metallurgiya, No 5, 1991, 23-27. (In Russian). It is r e p o r t e d t h a t Cr can be a d d e d to Fe powders in the form of organo-metallic compounds which decompose during heating. The s t r u c t u r e a n d properties of Fe alloys with Cr a d d e d in this way were i n v e s t i g a t e d a n d i n c r e a s e s in s t r e n g t h , hardness, impact and corrosion are reported for t h e sintered alloys. SUBSTITUTION OF IRON POWDER GRADES IN THE PRODUCTION OF AUTOMOBILE COMPONENTS
V.T. Koftelev, Poroshkovaya Metallurgiya, No 6,1991, 102o106. (In Russian). A p r o c e d u r e to enable a change of Fe powder typed in t h e p r o d u c t i o n of Fe-Cu compacts is described. The procedure was developed to avoid c h a n g e s in process routine following such a substitution. DEVELOPMENTS IN S I N T E R E D STAINLESS S T E E L
S. Shiming, ( R e s e a r c h Inst. of Powder Metallurgy, Beijing, China), PM Technology, Vol 10, No 1, 1992, 69-76. (In Chinese). The compositions, structures and properties of stainless steels m a n u f a c t u r e d in various countries are s u m m a r i z e d a n d discussed. An outline of possible future developments is presented. MICROSTRUCTURE OF ULTRAFINE CARBONYL IRON POWDER
X. Lin et al, ( C e n t r a l Iron a n d Steel Research Inst, China), Metallurgical TransactionsA, Vol 22A, No i1, 1991, 2709-2711. U l t r a f i n e c a r b o n y l Fe powder, 5 to 30 n m is size, w a s c h a r a c t e r i z e d a n d f o u n d to c o n s i s t of p a r t i c l e s of ¢~Fe
MPR July/August 1992 57
PM
enclosed in a skin of Fe304. Some grains were completely oxidized to Fe20.~ 5 to 10 nm in size with a hollow core. MAGNETIC PROPERTIES OF MECHANICALLY ALLOYED (M_A) BODY C E N T R E D CUBIC ( B C C ) IRON BASE ALLOYS
N. K a t a o k a et al, ( T o h o k u University, J a p a n ) , J Materials Science, Vol 26, No 17, 1991, 4621-4625. The s t r u c t u r e and magnetic properties of MA Fe base alloys with Zr, Hf, Co or Si additions, made from elemental powders or m i x t u r e s of elemental a n d alloy powders have been investigated, Fe rich alloys, (above 90% Fe) with Zr or Hf are reported to contain non-equilibrium BCC p h a s e s a n d to exhibit high values of coercivity a n d magnetization with zero magnetostriction. Fe-Co alloys were shown to have high values of permeability. MECHANICAL ALLOYING ( M A ) OF IRON-CARBON POWDER MIXTURES T. T a n a k a et al, (Osaka Industrial University, Osaka, J a p a n ) , J Less C o m m o n Metals, Vol 171, No 2, 1991, 237-247. Fe-graphite powder mixtures, in t h e range 17 to 90 at% C were subjected to MA in a ball mill. The p o w d e r s were characterized by a wide range of physical techniques. Amorphization and the formation of Fe3C or FevC3 were found in the ranges 17 to 25 at % C a n d 29 to 70 at% C respectively. Paramagnetic particles were found in the range 80 to 90 at% C.
Magnesium CONSOLIDATION OF AMORPHOUS MAGNESIUM-COPPER-YTTRIUM POWDERS WITH HIGH STRENGTH
LITERATURE
REVIEW
Investigations of t h e effects of grain size, density a n d porosity of t h e sintered blanks used in t h e making of Mo wire a n d t h e influence of process conditions are described. The structure/property relationships of t h e Mo wire are analyzed. It is considered t h a t powder particle size a n d s i n t e r i n g c o n d i t i o n s are t h e m a i n factors which determine the m i c r o s t r u c t u r e of t h e wire. O p t i m u m process conditions are outlined.
Titanium ENHANCEMENT OF PROPERTIES OF TITANIUM ALLOYS BY USING B L E N D E D ELEMENTAL POWDERS
M. Hagiwara et al, (National Research Inst. for Metals, J a p a n ) , Zairyo to Puroesu, Vol 3, No 5, 1990, 1621-1624. (In J a p a n e s e ) . The s t r u c t u r e a n d properties of PM Ti alloys are discussed. In particular the low levels of C1 a n d control of m i c r o s t r u c t u r e to a fine two p h a s e structure are considered. The p a p e r outlines t h e d e v e l o p m e n t of a n alloy, which c o n t a i n s a fine acicular phase, which is reported to have good fatigue a n d creep properties. PREPARATION OF AMORPHOUS TITANIUM-SILICON ALLOYS BY MECHANICAL ALLOYING
D. Parlapanski et al, (Higher Inst. of Mining a n d Geology, Sofia, B u l g a r i a ) , J Less C o m m o n Metals, Vol 171, No 2, 1991, 231236. It is shown t h a t a m o r p h o u s Ti-Si alloys c a n be p r o d u c e d by MA of e l e m e n t a l powder m i x t u r e s in a vibratory mill. The m e c h a n i s m of a m o r p h i z a t i o n was studied by X-ray diffraction, differential analysis and scanning electron microscopy.
S t r u c t u r e / p r o p e r t y relations in W heavy alloys a r e s u m m a r i z e d a n d reviewed. F r a c t u r e modes, effects of composition, contiguity of W particles a n d the effects of H a n d P are considered. RECENT ADVANCES IN T U N G S T E N AND ITS ALLOYS -- POWDERS AND D O P E D T U N G S T E N FILAMENTS
W. Yin et al, (Northwest Inst for NonFerrous Metals Research, C h i n a ) , Rare Metals a n d Materials Engineering, No 2, 1990, 2-10. (In Chinese). Recent advances in W powder a n d doped W filament technology are s u m m a r i z e d a n d discussed. Measures for t h e i m p r o v e m e n t of filament quality, purification of W a n d o p t i m i z a t i o n of process conditions, are outlined. The influences of powder quality a n d composition on structure, properties and quality of t h e W wires are discussed. INFLUENCES OF PARTICLE SIZE DISTRIBUTION ON THE PROPERTIES OF T U N G S T E N PLATES
Y. Shen, (Northwest Inst for Non-Ferrous Metals Research, China), Rare Metals a n d Materials Engineering, No 4, 1990, 35-40. (In Chinese). Investigation of the effects of W powder particle size d i s t r i b u t i o n on ductile -brittle transition, recrystallization behaviour, h a r d n e s s a n d p h o t o - e t c h i n g characteristics of t h e consolidated metal are described. The W was produced by CIP, sintering at 1200°C in H a n d in v a c u u m at 2700°C a n d rolling. It is reported t h a t good p r o p e r t i e s were o b t a i n e d w i t h p o w d e r s c o n t a i n i n g a b l e n d of coarse a n d fine p a r t i c l e s w h i c h gave a u n i f o r m g r a i n structure.
Coatings
Tungsten Y. Kawamura et al, (Tohoku University, Sendal, J a p a n ) , J J a p a n Soc P o w d e r a n d P o w d e r Metallurgy, Vol 38, No 7, 1991, 948-952. (In J a p a n e s e ) . The properties a n d applications of Mg25 at% Cu-10% Y alloys are discussed with respect to process conditions required to p r o d u c e fully d e n s e b u l k a m o r p h o u s materials from a m o r p h o u s powders. The alloys have a wide range of supercooled liquid. It is suggested t h a t the alloy h a s potential for use in lightweight applications.
Molybdenum II
IH
II
FABRICATION OF T U N G S T E N DISKS FOR LASER APPLICATIONS
P.S. Rajan et al, ( B h a b a Atomic Research Centre, Bombay, India), Trans P M Assoc o f India, Vol 18, 1991, 53-56. T h e d e v e l o p m e n t of a f a b r i c a t i o n sequence for the production of W disks for c o m p o n e n t s of Ar ion lasers is described. The disks, which had a density of 85%, were m a d e to close dimensional tolerances. The process route is described a n d it is reported t h a t t h e p e r f o r m a n c e of t h e disks is satisfactory.
MICROSTRUCTURE AND WORKABILITY OF MOLYBDENUM BAR U S E D IN THE PRODUCTION OF WIRE
STRUCTURE PROPERTY RELATIONSHIPS IN T U N G S T E N HEAVY ALLOYS
M. Shi a n d S. Yu, R a r e M e t a l s a n d Materials Engineering, No 4, 1990, 52-56. (In Chinese).
H. J i h u a et al, (University of Science a n d Technology, Beijing, China), P M Technology, Vol 10, No 1, 1992, 63-68. (In Chinese).
58 MPR July/August
ADVANCED LOW P R E S S U R E PLASMA APPLICATION IN PM
Sickinger a n d E. Muehlberger, (ElectroPlasma Inc., Irvine, California, USA), Powder Metall Int, Vol 24, No 2, 1992, 91-94. The p a p e r describes t h e process a n d a p p l i c a t i o n s of low p r e s s u r e p l a s m a s p r a y i n g of m e t a l p o w d e r s f o r t h e production of dense, pore free oxide free coatings with good adhesion to the s u b s t r a t e a n d with lower t h e r m a l stress. State-of-the-art production equipment, fully computerized for advanced levels of control, is described. INFLUENCE OF THE F R E E GAS VOLUME ON THE CHEMICAL VAPOUR DEPOSITION OF ALUMINA
J. Peng et al, (Technical University, Vienna, Austria), Int. J. Refractory Metals & H a r d Mater/a/s, Vol 10, No 4, 1991, 203-210. (In German).
Z-H. Chen et al, (Central South University of Technology, C h i n a ) J Less Common Metals, Vol 171, No 2, 1991, 187-194. It is shown t h a t a m o r p h o u s Al-10at% Y5% Ni alloy powder can be produced by rapid solidification. The characteristics a n d t h e r m a l s t a b i l i t y of t h e p o w d e r a r e discussed. The use of explosive compaction, v a c u u m hot pressing of h o t extrusion are reported to enable consolidation of the powder to amorphous, amorphous and microcrystalline, or microcrystalline bulk material, respectively, a n d the properties are described.
Beryllium MICRO YIELD STRENGTH OF BERYLLIUM CONSOLIDATED BY PM METHODS
B.G. Naik a n d V.IC Singhal, ( B h a b a Atomic Research Centre, Bombay, India), Trans, PMAssoc. of India, Vol 18, 1991, 31-35. The a p p l i c a t i o n s of s i n t e r e d Be are reviewed w i t h r e g a r d to p h y s i c a l a n d mechanical properties. The stability u n d e r stress, which is related to the rigidity, is quantified by micro yield s t r e n g t h (MYS). The d e v e l o p m e n t of a t e c h n i q u e for evaluation of MYS is described a n d t h e factors which influence it are discussed.
33 at% B was mechanically alloyed for 150 h o u r s a n d t h e n e x a m i n e d by X-ray diffraction, X-ray spectroscopy and d i f f e r e n t i a l s c a n n i n g c a l o r i m e t r y . The s t r u c t u r e s are reported to be d e p e n d e n t of t h e filling ratio of t h e mill (charge: void ratio, f:v). For a ratio of 1:1 only partial a m o r p h i z a t i o n is achieved a n d a steady state is reached after 25 h o u r s milling. For more energetic milling a t f:v o f 1:5 a m o r p h i z a t i o n is a l m o s t c o m p l e t e after 70 hours. In t h e final stages t h e f o r m a t i o n of t-Co2B is r e p o r t e d a n d a steady s t a t e exists between crystalline a n d a m o r p h o u s materials.
Copper PROCESS PARAMETERS FOR BONDING COPPER POWDER TO OXYGEN F R E E HIGH CONDUCTIVITY ( O F H C ) COPPER SUBSTRATE BY CIP AND SINTERING
G.~. Rao et al, (Defence Materials Research Laboratory, Hyderabad, India), Trans PM Assoc. of India, Vol 18, 1991, 27-30 The fabrication of a c o m p o n e n t in which Cu powder is b o n d e d to a n OFHC Cu s u b s t r a t e , b y C I P a n d s i n t e r i n g is described. The bond strength was evaluated by m e a n s of a s h e a r test a n d t h e process condition were optimized on t h e basis of t h e d e b o n d i n g test.
SINTERING OF COPPER COMPACTS WITH CHANNELS
V.G. Zatovsky et al, (Academy of Sciences of the ~ne, Kiev, Ukraine), Poroshkovaya Metallurgiya, No 5, 1991, 18-22. (In Russian). An investigation of the sintering of Cu compacts containing channels, which are introduced by t h e addition of fibres which d e c o m p o s e thermally, is described. The shrinkage of t h e c o m p o n e n t is reported to be greater t h a n t h e change in volume of t h e channels. Swelling is noted w h e n the fibres u s e d were b e l o w 0.3 m m a n d t h i s is a t t r i b u t e d to i m p e d e d r e m o v a l of t h e gaseous p r o d u c t s of decomposition of t h e fibres.
Iron and steel
Cobalt SOLID STATE REACTION IN MILLING OF COBALT-BORON POWDER MIXTURES
A. Corrias et al, (University of Cagliari, S a r d i n i a , Italy), J Materials Science, Vol 26, No 18, 1991, 5081-5084. A powder m i x t u r e consisting of Co with
SINTERING OF MOLYBDENUM ALLOYED PM S T E E L S PREPARED FROM ELEMENTAL POWDERS
H. Danninger, (Technical University, Vienna, Austria), Powder Metall. Int., Vol 24, No 2, 1992, 73-79 The p a p e r describes an investigation into the effects of sintering temperatures, in t h e r a n g e 1160 ° to 1360°C, on t h e
mechanical properties of sintered Fe-l.5% Mo-0.7%. It is reported t h a t a t r a n s i e n t liquid p h a s e is formed above 1230°C which results in a more h o m o g e n e o u s distribution o f Mo a n d c o n s e q u e n t l y improved mechanical p r o p e r t i e s of b o t h as-sintered a n d heat t r e a t e d materials. SURFACE DURABILITY OF THROUGHH A R D E N E D PM S T E E L GEARS
C. M a d h a v a n a n d I~ Gopinath, (Institute of Technology, Madras, I n d i a ) , Trans PM Assoe of India, Vol 18, 1991, 37-46. A rig for testing steel, 1.7% Ni-1.5% Cu0.8% Mo-0.5% C, gears is described. Wear is m o n i t o r e d by t o o t h thickness, weight loss, acoustic emission a n d Fe c o n t a m i n a t i o n of t h e oil. The m e c h a n i s m s are mild wear, pitting a n d surface fatigue. A wear rate e q u a t i o n is given a n d g e a r f a i l u r e is analysed. ALLOYING OF IRON POWDER BASE ALLOYS WITH CHROMIUM AND ITS COMPOUNDS
E_A. Mazurenko et al, Poroshkovaya Metallurgiya, No 5, 1991, 23-27. (In Russian). It is r e p o r t e d t h a t Cr can be a d d e d to Fe powders in the form of organo-metallic compounds which decompose during heating. The s t r u c t u r e a n d properties of Fe alloys with Cr a d d e d in this way were i n v e s t i g a t e d a n d i n c r e a s e s in s t r e n g t h , hardness, impact and corrosion are reported for t h e sintered alloys. SUBSTITUTION OF IRON POWDER GRADES IN THE PRODUCTION OF AUTOMOBILE COMPONENTS
V.T. Koftelev, Poroshkovaya Metallurgiya, No 6,1991, 102o106. (In Russian). A p r o c e d u r e to enable a change of Fe powder typed in t h e p r o d u c t i o n of Fe-Cu compacts is described. The procedure was developed to avoid c h a n g e s in process routine following such a substitution. DEVELOPMENTS IN S I N T E R E D STAINLESS S T E E L
S. Shiming, ( R e s e a r c h Inst. of Powder Metallurgy, Beijing, China), PM Technology, Vol 10, No 1, 1992, 69-76. (In Chinese). The compositions, structures and properties of stainless steels m a n u f a c t u r e d in various countries are s u m m a r i z e d a n d discussed. An outline of possible future developments is presented. MICROSTRUCTURE OF ULTRAFINE CARBONYL IRON POWDER
X. Lin et al, ( C e n t r a l Iron a n d Steel Research Inst, China), Metallurgical TransactionsA, Vol 22A, No i1, 1991, 2709-2711. U l t r a f i n e c a r b o n y l Fe powder, 5 to 30 n m is size, w a s c h a r a c t e r i z e d a n d f o u n d to c o n s i s t of p a r t i c l e s of ¢~Fe
MPR July/August 1992 57
PM
enclosed in a skin of Fe304. Some grains were completely oxidized to Fe20.~ 5 to 10 nm in size with a hollow core. MAGNETIC PROPERTIES OF MECHANICALLY ALLOYED (M_A) BODY C E N T R E D CUBIC ( B C C ) IRON BASE ALLOYS
N. K a t a o k a et al, ( T o h o k u University, J a p a n ) , J Materials Science, Vol 26, No 17, 1991, 4621-4625. The s t r u c t u r e and magnetic properties of MA Fe base alloys with Zr, Hf, Co or Si additions, made from elemental powders or m i x t u r e s of elemental a n d alloy powders have been investigated, Fe rich alloys, (above 90% Fe) with Zr or Hf are reported to contain non-equilibrium BCC p h a s e s a n d to exhibit high values of coercivity a n d magnetization with zero magnetostriction. Fe-Co alloys were shown to have high values of permeability. MECHANICAL ALLOYING ( M A ) OF IRON-CARBON POWDER MIXTURES T. T a n a k a et al, (Osaka Industrial University, Osaka, J a p a n ) , J Less C o m m o n Metals, Vol 171, No 2, 1991, 237-247. Fe-graphite powder mixtures, in t h e range 17 to 90 at% C were subjected to MA in a ball mill. The p o w d e r s were characterized by a wide range of physical techniques. Amorphization and the formation of Fe3C or FevC3 were found in the ranges 17 to 25 at % C a n d 29 to 70 at% C respectively. Paramagnetic particles were found in the range 80 to 90 at% C.
Magnesium CONSOLIDATION OF AMORPHOUS MAGNESIUM-COPPER-YTTRIUM POWDERS WITH HIGH STRENGTH
LITERATURE
REVIEW
Investigations of t h e effects of grain size, density a n d porosity of t h e sintered blanks used in t h e making of Mo wire a n d t h e influence of process conditions are described. The structure/property relationships of t h e Mo wire are analyzed. It is considered t h a t powder particle size a n d s i n t e r i n g c o n d i t i o n s are t h e m a i n factors which determine the m i c r o s t r u c t u r e of t h e wire. O p t i m u m process conditions are outlined.
Titanium ENHANCEMENT OF PROPERTIES OF TITANIUM ALLOYS BY USING B L E N D E D ELEMENTAL POWDERS
M. Hagiwara et al, (National Research Inst. for Metals, J a p a n ) , Zairyo to Puroesu, Vol 3, No 5, 1990, 1621-1624. (In J a p a n e s e ) . The s t r u c t u r e a n d properties of PM Ti alloys are discussed. In particular the low levels of C1 a n d control of m i c r o s t r u c t u r e to a fine two p h a s e structure are considered. The p a p e r outlines t h e d e v e l o p m e n t of a n alloy, which c o n t a i n s a fine acicular phase, which is reported to have good fatigue a n d creep properties. PREPARATION OF AMORPHOUS TITANIUM-SILICON ALLOYS BY MECHANICAL ALLOYING
D. Parlapanski et al, (Higher Inst. of Mining a n d Geology, Sofia, B u l g a r i a ) , J Less C o m m o n Metals, Vol 171, No 2, 1991, 231236. It is shown t h a t a m o r p h o u s Ti-Si alloys c a n be p r o d u c e d by MA of e l e m e n t a l powder m i x t u r e s in a vibratory mill. The m e c h a n i s m of a m o r p h i z a t i o n was studied by X-ray diffraction, differential analysis and scanning electron microscopy.
S t r u c t u r e / p r o p e r t y relations in W heavy alloys a r e s u m m a r i z e d a n d reviewed. F r a c t u r e modes, effects of composition, contiguity of W particles a n d the effects of H a n d P are considered. RECENT ADVANCES IN T U N G S T E N AND ITS ALLOYS -- POWDERS AND D O P E D T U N G S T E N FILAMENTS
W. Yin et al, (Northwest Inst for NonFerrous Metals Research, C h i n a ) , Rare Metals a n d Materials Engineering, No 2, 1990, 2-10. (In Chinese). Recent advances in W powder a n d doped W filament technology are s u m m a r i z e d a n d discussed. Measures for t h e i m p r o v e m e n t of filament quality, purification of W a n d o p t i m i z a t i o n of process conditions, are outlined. The influences of powder quality a n d composition on structure, properties and quality of t h e W wires are discussed. INFLUENCES OF PARTICLE SIZE DISTRIBUTION ON THE PROPERTIES OF T U N G S T E N PLATES
Y. Shen, (Northwest Inst for Non-Ferrous Metals Research, China), Rare Metals a n d Materials Engineering, No 4, 1990, 35-40. (In Chinese). Investigation of the effects of W powder particle size d i s t r i b u t i o n on ductile -brittle transition, recrystallization behaviour, h a r d n e s s a n d p h o t o - e t c h i n g characteristics of t h e consolidated metal are described. The W was produced by CIP, sintering at 1200°C in H a n d in v a c u u m at 2700°C a n d rolling. It is reported t h a t good p r o p e r t i e s were o b t a i n e d w i t h p o w d e r s c o n t a i n i n g a b l e n d of coarse a n d fine p a r t i c l e s w h i c h gave a u n i f o r m g r a i n structure.
Coatings
Tungsten Y. Kawamura et al, (Tohoku University, Sendal, J a p a n ) , J J a p a n Soc P o w d e r a n d P o w d e r Metallurgy, Vol 38, No 7, 1991, 948-952. (In J a p a n e s e ) . The properties a n d applications of Mg25 at% Cu-10% Y alloys are discussed with respect to process conditions required to p r o d u c e fully d e n s e b u l k a m o r p h o u s materials from a m o r p h o u s powders. The alloys have a wide range of supercooled liquid. It is suggested t h a t the alloy h a s potential for use in lightweight applications.
Molybdenum II
IH
II
FABRICATION OF T U N G S T E N DISKS FOR LASER APPLICATIONS
P.S. Rajan et al, ( B h a b a Atomic Research Centre, Bombay, India), Trans P M Assoc o f India, Vol 18, 1991, 53-56. T h e d e v e l o p m e n t of a f a b r i c a t i o n sequence for the production of W disks for c o m p o n e n t s of Ar ion lasers is described. The disks, which had a density of 85%, were m a d e to close dimensional tolerances. The process route is described a n d it is reported t h a t t h e p e r f o r m a n c e of t h e disks is satisfactory.
MICROSTRUCTURE AND WORKABILITY OF MOLYBDENUM BAR U S E D IN THE PRODUCTION OF WIRE
STRUCTURE PROPERTY RELATIONSHIPS IN T U N G S T E N HEAVY ALLOYS
M. Shi a n d S. Yu, R a r e M e t a l s a n d Materials Engineering, No 4, 1990, 52-56. (In Chinese).
H. J i h u a et al, (University of Science a n d Technology, Beijing, China), P M Technology, Vol 10, No 1, 1992, 63-68. (In Chinese).
58 MPR July/August
ADVANCED LOW P R E S S U R E PLASMA APPLICATION IN PM
Sickinger a n d E. Muehlberger, (ElectroPlasma Inc., Irvine, California, USA), Powder Metall Int, Vol 24, No 2, 1992, 91-94. The p a p e r describes t h e process a n d a p p l i c a t i o n s of low p r e s s u r e p l a s m a s p r a y i n g of m e t a l p o w d e r s f o r t h e production of dense, pore free oxide free coatings with good adhesion to the s u b s t r a t e a n d with lower t h e r m a l stress. State-of-the-art production equipment, fully computerized for advanced levels of control, is described. INFLUENCE OF THE F R E E GAS VOLUME ON THE CHEMICAL VAPOUR DEPOSITION OF ALUMINA
J. Peng et al, (Technical University, Vienna, Austria), Int. J. Refractory Metals & H a r d Mater/a/s, Vol 10, No 4, 1991, 203-210. (In German).