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Evolution of pore shape during deformation of porous bodies
PM combustion, is shown to consist of small TiC crystals in an a m o r p h o u s A1203 base matrix phase. The Vicker's h a r d n e s s was 32.7 GPa. C E N T R I F U G A L C O M P A C T I O N OF VARIOUS S H A P E S
S. Tashima et al (Hiroshima University, Hiroshima, J a p a n ) , J ,Japan Soc Powder and Powder Metallurgy, Vol 40, No 1, 1993, 12-15. (In J a p a n e s e ) . It is pointed out t h a t because centrifugal forces act unidirectionally only a limited range of s h a p e s may be possible. The effects of p a r t i c l e m o v e m e n t in t h e r e v e r s e direction or p e r p e n d i c u l a r to the direction of the centrifugal force were investigated using slips of Al20:~ with 25% water. It is reported that compacts with uniform density could be p r o d u c e d if reverse or perpendicular particle m o v e m e n t could be i n d u c e d . The d e s i g n of d i e s u s e d is described and discussed. E L E C T R O I M P A C T C O M P A C T I O N OF P O W D E R S -- M E C H A N I C S , STRUCTURE AND PROPERTIES
S.T.S. A1-Hassani et al ( U n i v e r s i t y of Manchester Inst of Science and Technology, M a n c h e s t e r , UK), Materials and Manufacturing Proce.sses, Vol 8, No 3, 1993, 285-298. An electroimpaet process for compaction is d e s c r i b e d . Electric d i s c h a r g e a n d d y n a m i c p r o c e s s e s are considered. The effects of process c o n d i t i o n s a n d m a t e r i a l s t r u c t u r e on properties of preforms are described. A mathematical mode is presented. Optimum properties are said to be obtained when the electrical discharge causes i n t e r p a r t i c l e fusion at the i n s t a n t of peak dynamic compaction pressure.
SlNTERING LASER P R O C E S S I N G OF M E T A L L I C AND INTERMETALLIC SURFACES
E.J. Petit, (France Telecom, Bagneaux, F r a n c e ) , Materials and Manufacturing Processes, Vol 8, No 3, 1993, 299-314. The use of laser t e c h n o l o g y in t h e processing of metals, alloys and intermetallic materials is reviewed with r e s p e c t to t h e a d v a n t a g e s a c c r u i n g . A p p l i c a t i o n s to s u r f a c e h a r d e n i n g , cleaning, surface alloying and the application of coatings are considered as e x t e n s i o n s of existing processes or the introduction of new ones.
LITERATURE
REVIEW
T e d d i n g t o n , Middlesex, UK), Materials World, Vol 1, No 5, 1993, 281-283. The r o l e of f r i c t i o n a n d w e a r in engineering and technology is discussed with reference to the need for reliable d a t a on the tribological p r o p e r t i e s of materials. Testing machines and test conditions are considered and the importance of interlaboratory collaboration is emphasized. It is noted t h a t machine dynamics have often been neglected during wear testing and tests of a material on different m a c h i n e s is described. The need for a framework for wear test methodology is discussed. M O D E L L I N G OF ROD GROWTH D U R I N G SPRAY F O R M I N G
H.C. Lee et al (Seoul National University, Seoul, Korea), J Korean Inst of Metals, Vol 30, No 9, 1992, 107-1077. (In Korean). A model for the s h a p e of a rod, u n d e r steady state conditions during spray forming, is described. It is a s s u m e d t h a t t h e s p r a y is p a r a l l e l a n d s t r i k e s t h e substrate perpendicularly. Time to reach steady state conditions is calculated and agrees with the results from a t r a n s i e n t model. The radius of the rod is proportional to the square root of the metal flow and inversely proportional to the withdrawal rate. EVOLUTION OF P O R E S H A P E D U R I N G D E F O R M A T I O N OF P O R O U S B O D I E S
A.L. M a k s i m e n k o et al, Poroshkovaya Metallurgiya, No 5, 1992, 13-18. (In Russian). A n i s t r o p y of p r o p e r t i e s o f p o r o u s m a t e r i a l s is s h o w n to be r e l a t e d to changes in pore shape. A study of pore shape evolution during plane upset deformation, with respect to deformation mechanisms, is described. Correlations are established between deformation s p e e d and pore surface velocity. E F F E C T S OF R O L L I N G O N S T R U C T U R E OF A L U M I N I U M N I T R I D E POWDER A N D HOT C O M P A C T E D MATERIAL
O.A. Katrus et al, Poroshkovaya Metallurgiya, No 5, 1992, 59-63. (In Russian). The effects of AIN additions on the s t r u c t u r e and m e c h a n i c a l p r o p e r t i e s of h o t - c o m p a c t e d materials was investigated. It is r e p o r t e d t h a t A1N p r o m o t e s d e n s i f i c a t i o n a n d l e a d s to e n h a n c e d properties. E F F E C T OF C O N V E C T I O N I N VOIDS ON H E A T T R A N S F E R I N POLYCAPILLARY COMPOSITE MATERIALS
FUNDAMENTALS WEAR METROLOGY -- T H E A R T OF D E T E R M I N A T I O N OF M A T E R I A L PERFORMANCE
M. Gee
(National
Physical Laboratory,
L.I. Tuchinsky and E.M. Veksler, Poroshkovaya MetaUurgiya, No 5, 1992, 80-84. (In Russian). Thermal c o n d u c t i v i t i e s of c o m p o s i t e materials, containing capillary channels in which convection can occur, was
investigated with regard to the thermal conductivities of t h e constituents. It is s h o w n t h a t it is p o s s i b l e to m a k e a correction for the convection in calculating heat transfer through the material.
PRODUCTS: Aluminium E F F E C T OF Z I R C O N I U M OR N I C K E L ON P R E C I P I T A T I O N H A R D E N I N G I N A MANGANESE-CHROMIUM ALUMINIUM ALLOY
H.T. Shin et al (Nihon University, Narashino, J a p a n ) , J Japan Inst of Metals, Vol 56, No 11, 1992, 1248-1256. (In J a p a n e s e ) . An i n v e s t i g a t i o n o f p r e c i p i t a t i o n h a r d e n i n g in a s u p e r s a t u r a t e d s o l i d solution in A1-8% Mn-2% Cr, w i t h / w i t h o u t Ni or Zr, is described. Flaky powder was produced by g a s a t o m i z a t i o n and i m p i n g e m e n t on a w a t e r cooled Cu roller and consolidated by cold pressing, vacuum d e g a s s i n g a n d h o t e x t r u s i o n . An age h a r d e n i n g peak was found at 400°C in Zr alloys. The p h a s e s responsible ibr aging were identified as ZrAlj, (Mn, Cr)All2 and Al16Mn3Ni. Ni is r e p o r t e d to delay the onset of aging. Increases in tensile strength was found for both Ni and Zr alloys but with low ductility. MICROSTRUCTURE AND THERMAL STABILITY OF RAPIDLY S O L I D I F I E D A L U M I N I U M - T I T A N I U M ALLOY
ICH. Oh et al (Korea Inst. of Science and Technology, Seoul, Korea), J Korean Inst of Metals, Vol 30, No 10, 1992, 1196-1204. (In Korean). N atomized powders and hot e x t r u d e d Al-10 wt% Ti w e r e c h a r a c t e r i z e d . The powders were spherical with a mean particle size of 50 ~m and a grain size 2 to 3 /~m w i t h TiA13 p a r t i c l e s . The material, after extrusion at an extrusion ration of 17:1 consisted of an ~ A1 matrix, grain size 2 pro, containing equilibrium TiAIa particles. C H A R A C T E R I Z A T I O N OF CENTRIFUGALLY ATOMIZED A L U M I N I U M ALLOY POWDER A N D P R O P E R T I E S OF S T R I P
J.T. Moon et al (Hong Ik University, Seoul, Korea), J Korean Inst. of Metals, Vol 30, No l l , 1992, 1344-1353. (In Korean). It is r e p o r t e d t h a t cylindrically s h a p e d powders of A1-8.5% Pb-l.5% Sn-4% Si-(1 to 5)% Cu w e r e p r o d u c e d by c e n t r i f u g a l atomization. A clad material of pure Al at both surfaces and the alloy in the core was p r o d u c e d by powder rolling with sufficient green strength to p e r m i t handling after 70% r e d u c t i o n by rolling. The m a t e r i a l was sintered at 500 °C. The clad alloy was roll b o n d e d onto cleaned mild steel strip by 25% reduction which resulted in a sufficiently strong bond.
MPR July\August 1993 43
S. Tashima et al (Hiroshima University, Hiroshima, J a p a n ) , J ,Japan Soc Powder and Powder Metallurgy, Vol 40, No 1, 1993, 12-15. (In J a p a n e s e ) . It is pointed out t h a t because centrifugal forces act unidirectionally only a limited range of s h a p e s may be possible. The effects of p a r t i c l e m o v e m e n t in t h e r e v e r s e direction or p e r p e n d i c u l a r to the direction of the centrifugal force were investigated using slips of Al20:~ with 25% water. It is reported that compacts with uniform density could be p r o d u c e d if reverse or perpendicular particle m o v e m e n t could be i n d u c e d . The d e s i g n of d i e s u s e d is described and discussed. E L E C T R O I M P A C T C O M P A C T I O N OF P O W D E R S -- M E C H A N I C S , STRUCTURE AND PROPERTIES
S.T.S. A1-Hassani et al ( U n i v e r s i t y of Manchester Inst of Science and Technology, M a n c h e s t e r , UK), Materials and Manufacturing Proce.sses, Vol 8, No 3, 1993, 285-298. An electroimpaet process for compaction is d e s c r i b e d . Electric d i s c h a r g e a n d d y n a m i c p r o c e s s e s are considered. The effects of process c o n d i t i o n s a n d m a t e r i a l s t r u c t u r e on properties of preforms are described. A mathematical mode is presented. Optimum properties are said to be obtained when the electrical discharge causes i n t e r p a r t i c l e fusion at the i n s t a n t of peak dynamic compaction pressure.
SlNTERING LASER P R O C E S S I N G OF M E T A L L I C AND INTERMETALLIC SURFACES
E.J. Petit, (France Telecom, Bagneaux, F r a n c e ) , Materials and Manufacturing Processes, Vol 8, No 3, 1993, 299-314. The use of laser t e c h n o l o g y in t h e processing of metals, alloys and intermetallic materials is reviewed with r e s p e c t to t h e a d v a n t a g e s a c c r u i n g . A p p l i c a t i o n s to s u r f a c e h a r d e n i n g , cleaning, surface alloying and the application of coatings are considered as e x t e n s i o n s of existing processes or the introduction of new ones.
LITERATURE
REVIEW
T e d d i n g t o n , Middlesex, UK), Materials World, Vol 1, No 5, 1993, 281-283. The r o l e of f r i c t i o n a n d w e a r in engineering and technology is discussed with reference to the need for reliable d a t a on the tribological p r o p e r t i e s of materials. Testing machines and test conditions are considered and the importance of interlaboratory collaboration is emphasized. It is noted t h a t machine dynamics have often been neglected during wear testing and tests of a material on different m a c h i n e s is described. The need for a framework for wear test methodology is discussed. M O D E L L I N G OF ROD GROWTH D U R I N G SPRAY F O R M I N G
H.C. Lee et al (Seoul National University, Seoul, Korea), J Korean Inst of Metals, Vol 30, No 9, 1992, 107-1077. (In Korean). A model for the s h a p e of a rod, u n d e r steady state conditions during spray forming, is described. It is a s s u m e d t h a t t h e s p r a y is p a r a l l e l a n d s t r i k e s t h e substrate perpendicularly. Time to reach steady state conditions is calculated and agrees with the results from a t r a n s i e n t model. The radius of the rod is proportional to the square root of the metal flow and inversely proportional to the withdrawal rate. EVOLUTION OF P O R E S H A P E D U R I N G D E F O R M A T I O N OF P O R O U S B O D I E S
A.L. M a k s i m e n k o et al, Poroshkovaya Metallurgiya, No 5, 1992, 13-18. (In Russian). A n i s t r o p y of p r o p e r t i e s o f p o r o u s m a t e r i a l s is s h o w n to be r e l a t e d to changes in pore shape. A study of pore shape evolution during plane upset deformation, with respect to deformation mechanisms, is described. Correlations are established between deformation s p e e d and pore surface velocity. E F F E C T S OF R O L L I N G O N S T R U C T U R E OF A L U M I N I U M N I T R I D E POWDER A N D HOT C O M P A C T E D MATERIAL
O.A. Katrus et al, Poroshkovaya Metallurgiya, No 5, 1992, 59-63. (In Russian). The effects of AIN additions on the s t r u c t u r e and m e c h a n i c a l p r o p e r t i e s of h o t - c o m p a c t e d materials was investigated. It is r e p o r t e d t h a t A1N p r o m o t e s d e n s i f i c a t i o n a n d l e a d s to e n h a n c e d properties. E F F E C T OF C O N V E C T I O N I N VOIDS ON H E A T T R A N S F E R I N POLYCAPILLARY COMPOSITE MATERIALS
FUNDAMENTALS WEAR METROLOGY -- T H E A R T OF D E T E R M I N A T I O N OF M A T E R I A L PERFORMANCE
M. Gee
(National
Physical Laboratory,
L.I. Tuchinsky and E.M. Veksler, Poroshkovaya MetaUurgiya, No 5, 1992, 80-84. (In Russian). Thermal c o n d u c t i v i t i e s of c o m p o s i t e materials, containing capillary channels in which convection can occur, was
investigated with regard to the thermal conductivities of t h e constituents. It is s h o w n t h a t it is p o s s i b l e to m a k e a correction for the convection in calculating heat transfer through the material.
PRODUCTS: Aluminium E F F E C T OF Z I R C O N I U M OR N I C K E L ON P R E C I P I T A T I O N H A R D E N I N G I N A MANGANESE-CHROMIUM ALUMINIUM ALLOY
H.T. Shin et al (Nihon University, Narashino, J a p a n ) , J Japan Inst of Metals, Vol 56, No 11, 1992, 1248-1256. (In J a p a n e s e ) . An i n v e s t i g a t i o n o f p r e c i p i t a t i o n h a r d e n i n g in a s u p e r s a t u r a t e d s o l i d solution in A1-8% Mn-2% Cr, w i t h / w i t h o u t Ni or Zr, is described. Flaky powder was produced by g a s a t o m i z a t i o n and i m p i n g e m e n t on a w a t e r cooled Cu roller and consolidated by cold pressing, vacuum d e g a s s i n g a n d h o t e x t r u s i o n . An age h a r d e n i n g peak was found at 400°C in Zr alloys. The p h a s e s responsible ibr aging were identified as ZrAlj, (Mn, Cr)All2 and Al16Mn3Ni. Ni is r e p o r t e d to delay the onset of aging. Increases in tensile strength was found for both Ni and Zr alloys but with low ductility. MICROSTRUCTURE AND THERMAL STABILITY OF RAPIDLY S O L I D I F I E D A L U M I N I U M - T I T A N I U M ALLOY
ICH. Oh et al (Korea Inst. of Science and Technology, Seoul, Korea), J Korean Inst of Metals, Vol 30, No 10, 1992, 1196-1204. (In Korean). N atomized powders and hot e x t r u d e d Al-10 wt% Ti w e r e c h a r a c t e r i z e d . The powders were spherical with a mean particle size of 50 ~m and a grain size 2 to 3 /~m w i t h TiA13 p a r t i c l e s . The material, after extrusion at an extrusion ration of 17:1 consisted of an ~ A1 matrix, grain size 2 pro, containing equilibrium TiAIa particles. C H A R A C T E R I Z A T I O N OF CENTRIFUGALLY ATOMIZED A L U M I N I U M ALLOY POWDER A N D P R O P E R T I E S OF S T R I P
J.T. Moon et al (Hong Ik University, Seoul, Korea), J Korean Inst. of Metals, Vol 30, No l l , 1992, 1344-1353. (In Korean). It is r e p o r t e d t h a t cylindrically s h a p e d powders of A1-8.5% Pb-l.5% Sn-4% Si-(1 to 5)% Cu w e r e p r o d u c e d by c e n t r i f u g a l atomization. A clad material of pure Al at both surfaces and the alloy in the core was p r o d u c e d by powder rolling with sufficient green strength to p e r m i t handling after 70% r e d u c t i o n by rolling. The m a t e r i a l was sintered at 500 °C. The clad alloy was roll b o n d e d onto cleaned mild steel strip by 25% reduction which resulted in a sufficiently strong bond.
MPR July\August 1993 43