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Changes in pore structure of sintered iron compacts of diffusion in of alloy elements
PM
Cobalt C O N S O L I D A T I O N OF MECHANICALLY ALLOYED COBALT ALLOY BY HOT ISOSTATIC PRESSING
It. Kimura et al (National Defence Academy, Yokosuka, J a p a n ) , J Japan Inst of Metals, Vol 56, No 7. 1992, 833 841, (In .lapanese ). Novel p r o c e s s i n g of a m o r p h o u s MA p o w d e r , b a s e d on a v i s c o u s f l o w mechanism, is described for Co-15 at% Nb-5.5% Zr alloy. The HIP process was s t u d i e d by t h e r m o m e c h a n i c a l a n a l y s i s (TMA) and o p t i m u m process conditions are given. Shrinkage was detected below the onset of recrystallization (T,.) and the TMA r e s u l t s a l l o w e d d e t e r m i n a t i o n of t h e displacement rate, the ~dscosity. A glass transition (T,) and o t h e r factors which are shown to fit an Arhenius type of equation with an activation energy of 221 tel/tool. HIP in an evacuated capsule between Tg and %. and 195 MPa is r e p o r t e d to yield a m o r p h o u s high density material.
Copper D E F O R M A T I O N P R O C E S S E D WIRE P R E P A R E D FROM GAS A T O M I Z E D C O P P E R - N I O B I U M ALLOY P O W D E R S
T.W. Ellis et al (Iowa State University, Ames, Iowa, USA), Metallurgical Trans A, Vol 24A, No 1, 1993, 21-26. The production of Cu-20 vol% Nb wire by d e f o r m a t i o n p r o c e s s i n g of b i l l e t s prepared from high pressure gas atomized powders is described. It is reported t h a t the deformalion processed PM material had superior properties to wire produced from arc melted ingots at the same level of deff)rmation. This is a t t r i b u t e d to t h e smaller Nb dendrite size in the powders. The electrical conductivity of PM wire was lower than t h a t of the ingot wire. STRENGTH AND ELECTRICAL CONDUCTIVITY OF C O P P E R - I R O N WIRE P R E P A R E D FROM P O W D E R S
G.A. J e r m a n et al (Iowa State University, Ames, h)wa, USA), Metallurgical Trans A, Vol 24A, No l, 19.q3, 35-42. It is r e p o r t e d t h a t d e f o r m a t i o n processing has been used to p r e p a r e Cu15 vol% Fe alloy wire from elemental high purity gas atomized Cu and commercial purity Fe pnwder mixtures. Strict process control is shown to result in the production of C u - F e alloy w i r e s w i t h s t r e n g t h / conductivity properties matching those of Cu-Nb, Cu-Ta and Cu-Cr alloys.
Iron and steel E F F E C T S OF P A R T I C L E SIZE ON M A G N E T I C S U S C E P T I B I L I T Y OF A T O M I Z E D S T A I N L E S S S T E E L POWDER
G. Gase and P. Bracconi
62
MPR June 1993
(University of
LITERATURE
REVIEW
Burgundy, Dijon, France), Metallurgical TransA, Vol 23A, No 12, 1992, 2917-2921. Measurements of the magnetic susceptibility of N atomized 304L stainless steel powder are reported. Effects of field intensity and particle size were studied using the Faraday technique. Ferromagnetic and paramagnetic c o n t r i b u t i o n s to t h e s u s c e p t i b i l i t y are d e m o n s t r a t e d as a flmction of particle size. It is shown t h a t the ferromagnetic contribution arises from the precipitation of primary ferrite during atomization. The effect of surface Fe oxide is considered to be negligible. C H A N G E S IN P O R E S T R U C T U R E OF S I N T E R E D I R O N C O M P A C T S OF D I F F U S I O N IN OF ALLOY E L E M E N T S
T-W. Lim and K. Hayashi (University of Tokyo, Tokyo, J a p a n ) , J Japan Inst of Metals, Vol 56, No 7, 1992, 828-832. (In Japanese). A hypothesis t h a t partial or complete densification of sintered Fe is d e p e n d e n t on w h e t h e r the pressure (P~.o), arising from the reduction of oxides by impurities and t r a p p e d in pores, is greater or less t h a n the surface stress is r e p o r t e d to be t e s t e d by the e x p e r i m e n t s described. It is reported, (a) t h a t elements such as Mo did not decrease Pco but Nb did; (b) diffusion of C resulted in clusters of pores near oxide particles close to the surface; and (c) the results are considered to s u p p o r t the hypothesis. MICROSTRUCTURE AND MECHANICAL P R O P E R T I E S OF IRON-CHROMIUMA L U M I N I U M ALLOYS WITH C E R I U M
K. Mizuuchi et al (Osaka Technical Research Inst, Osaka, J a p a n ) , J Japan Inst of Metals, Vol 56, No 8, 1992, 930-937. (In Japanese). The effects of additions of Ce, up to 0.7 wt%, on the sintering and mechanical properties of Fe-30 wt% Cr-5% A1 alloys, p r e p a r e d from rapidly solidified powder, were investigated. Without Ce the alloys s i n t e r e d s a t i s f a c t o r i l y a b o v e 1400°C r e a c h i n g a grain size of 30 p m a f t e r 4 hours giving a tensile s t r e n g t h of 350 to 450 MPa and 2 to 3% elongation, Ce was found to increase surface oxidation which c o u l d be i n h i b i t e d by r o t a t i n g w a t e r atomization u n d e r Ar. the tensile s t r e n g t h of the 0.7% Ce alloy is reported to be 210 MPa b u t to be s u p e r i o r to t h e equivalent east alloy. S I N T E R I N G M E C H A N I S M S IN AUSTENITIC STAINLESS STEEL AND E F F E C T ON M E C H A N I C A L PROPERTIES
H. Kyogoku et al (Industrial Research Inst of Hiroshima, Fukuyama, J a p a n ) , J Japan Inst of Metals, Vol 56, No 9, 1992, 10721077. (In J a p a n e s e ) . The production of stainless steel by MIM from 9 pm powder is described. Sintering
was at 1300 to 1400:C at a pressure of 1 Pa for 0.5 to 4 hours. Image analysis was used to determine changes in porosity and grain size and it is reported t h a t the transition from pore shrinkage to growth and the coefficient of pinning force were inversely d e p e n d e n t on the grain size. Grain growth followed a cubic law a n d t h e t e n s i l e s t r e n g t h of t h e s i n t e r e d c o m p a c t was linearly related to the porosity. The prool stress conformed with the Hall-Petch relationship. C A R B U R I Z A T I O N OF A U S T E N I T E D U R I N G S I N T E R I N G O F IRONGRAPHITE POWDER COMPACTS
R.Z. Vlasyuk, Poroshkovaya Metallurgiya No 3, 1992, 34-37. (In Russian). Absorption of C during sintering, in the austenitic range, of Fe-graphite m i x t u r e s was studied by h i g h t e m p e r a t u r e radiography and metallographic methods. The activity of (" in solution in Fe al different stages was determined Correlations between strength and s t r u c t u r e of the resultant steel and (' solution are established. E F F E C T S OF E L E C T R O T H E R M A L T R E A T M E N T ON S T R U C T U R E A N D FAILURE D U C T I L I T Y OF S I N T E R E D IRON
A.S. Drachinsky el al, Poroshkovaya Metal lurgiya, No 3, 1992, 89-91, (In Russian). The fracture toughness, K~(., of sintered steel was studied within regard to the effects of alloy element distribution and porosity. It is shown t h a t an electrothermal t r e a t m e n t e l i m i n a t e s an a n o m a l o u s reduction, i t is s h o w n that a,~ e l e c t r o t h e r m a l t r e a t m e n t e l i m i n a t e s an a n o m a l o u s reduction in K~¢ which was attributed to segregation of alloy elements at grain boundaried. /Mr increase in K~,. after aging is reported aml this is attributed to t h e n u m b e r a n d d i s t r i b u t i n n of dislocations. HOT S T A M P I N G OF C O P P E R - S T E E L S
S.G. Napara-Volgina, Po,oshkovaya Metal lurgiya, No 4, 1992, 25-28. (In Russian) An i n v e s t i g a t i o n of t h e e f f e c t s (,i p r o d u c t i o n c o n d i t i o n s on p r o p e r t i e s of h o t - s t a m p e d steel c o m p o n e n t s containing 2.5 to 8% Cu is described. It is shown tha! the properties var3 wilh process parameters. Particular attention is given to the alloy with 5% Cu and the effects ol %C in the range 0.2 to 0.3%. It is shown that the strength can reach 900 ~o 1050 MPa with l0 to 12% elongation. I N C R E A S E IN C,O R R O S I O N R E S I S T A N C E BY D I F F U S I O N P L A T I N G OF C H R O M I U M ON P O R O U S IRON
I.S. Litmanovich a n d
YM. Zolotovitsky,
Poroshkovaya Metallurqiya, No 4, 1992, 28-31. (In Russian).
Cobalt C O N S O L I D A T I O N OF MECHANICALLY ALLOYED COBALT ALLOY BY HOT ISOSTATIC PRESSING
It. Kimura et al (National Defence Academy, Yokosuka, J a p a n ) , J Japan Inst of Metals, Vol 56, No 7. 1992, 833 841, (In .lapanese ). Novel p r o c e s s i n g of a m o r p h o u s MA p o w d e r , b a s e d on a v i s c o u s f l o w mechanism, is described for Co-15 at% Nb-5.5% Zr alloy. The HIP process was s t u d i e d by t h e r m o m e c h a n i c a l a n a l y s i s (TMA) and o p t i m u m process conditions are given. Shrinkage was detected below the onset of recrystallization (T,.) and the TMA r e s u l t s a l l o w e d d e t e r m i n a t i o n of t h e displacement rate, the ~dscosity. A glass transition (T,) and o t h e r factors which are shown to fit an Arhenius type of equation with an activation energy of 221 tel/tool. HIP in an evacuated capsule between Tg and %. and 195 MPa is r e p o r t e d to yield a m o r p h o u s high density material.
Copper D E F O R M A T I O N P R O C E S S E D WIRE P R E P A R E D FROM GAS A T O M I Z E D C O P P E R - N I O B I U M ALLOY P O W D E R S
T.W. Ellis et al (Iowa State University, Ames, Iowa, USA), Metallurgical Trans A, Vol 24A, No 1, 1993, 21-26. The production of Cu-20 vol% Nb wire by d e f o r m a t i o n p r o c e s s i n g of b i l l e t s prepared from high pressure gas atomized powders is described. It is reported t h a t the deformalion processed PM material had superior properties to wire produced from arc melted ingots at the same level of deff)rmation. This is a t t r i b u t e d to t h e smaller Nb dendrite size in the powders. The electrical conductivity of PM wire was lower than t h a t of the ingot wire. STRENGTH AND ELECTRICAL CONDUCTIVITY OF C O P P E R - I R O N WIRE P R E P A R E D FROM P O W D E R S
G.A. J e r m a n et al (Iowa State University, Ames, h)wa, USA), Metallurgical Trans A, Vol 24A, No l, 19.q3, 35-42. It is r e p o r t e d t h a t d e f o r m a t i o n processing has been used to p r e p a r e Cu15 vol% Fe alloy wire from elemental high purity gas atomized Cu and commercial purity Fe pnwder mixtures. Strict process control is shown to result in the production of C u - F e alloy w i r e s w i t h s t r e n g t h / conductivity properties matching those of Cu-Nb, Cu-Ta and Cu-Cr alloys.
Iron and steel E F F E C T S OF P A R T I C L E SIZE ON M A G N E T I C S U S C E P T I B I L I T Y OF A T O M I Z E D S T A I N L E S S S T E E L POWDER
G. Gase and P. Bracconi
62
MPR June 1993
(University of
LITERATURE
REVIEW
Burgundy, Dijon, France), Metallurgical TransA, Vol 23A, No 12, 1992, 2917-2921. Measurements of the magnetic susceptibility of N atomized 304L stainless steel powder are reported. Effects of field intensity and particle size were studied using the Faraday technique. Ferromagnetic and paramagnetic c o n t r i b u t i o n s to t h e s u s c e p t i b i l i t y are d e m o n s t r a t e d as a flmction of particle size. It is shown t h a t the ferromagnetic contribution arises from the precipitation of primary ferrite during atomization. The effect of surface Fe oxide is considered to be negligible. C H A N G E S IN P O R E S T R U C T U R E OF S I N T E R E D I R O N C O M P A C T S OF D I F F U S I O N IN OF ALLOY E L E M E N T S
T-W. Lim and K. Hayashi (University of Tokyo, Tokyo, J a p a n ) , J Japan Inst of Metals, Vol 56, No 7, 1992, 828-832. (In Japanese). A hypothesis t h a t partial or complete densification of sintered Fe is d e p e n d e n t on w h e t h e r the pressure (P~.o), arising from the reduction of oxides by impurities and t r a p p e d in pores, is greater or less t h a n the surface stress is r e p o r t e d to be t e s t e d by the e x p e r i m e n t s described. It is reported, (a) t h a t elements such as Mo did not decrease Pco but Nb did; (b) diffusion of C resulted in clusters of pores near oxide particles close to the surface; and (c) the results are considered to s u p p o r t the hypothesis. MICROSTRUCTURE AND MECHANICAL P R O P E R T I E S OF IRON-CHROMIUMA L U M I N I U M ALLOYS WITH C E R I U M
K. Mizuuchi et al (Osaka Technical Research Inst, Osaka, J a p a n ) , J Japan Inst of Metals, Vol 56, No 8, 1992, 930-937. (In Japanese). The effects of additions of Ce, up to 0.7 wt%, on the sintering and mechanical properties of Fe-30 wt% Cr-5% A1 alloys, p r e p a r e d from rapidly solidified powder, were investigated. Without Ce the alloys s i n t e r e d s a t i s f a c t o r i l y a b o v e 1400°C r e a c h i n g a grain size of 30 p m a f t e r 4 hours giving a tensile s t r e n g t h of 350 to 450 MPa and 2 to 3% elongation, Ce was found to increase surface oxidation which c o u l d be i n h i b i t e d by r o t a t i n g w a t e r atomization u n d e r Ar. the tensile s t r e n g t h of the 0.7% Ce alloy is reported to be 210 MPa b u t to be s u p e r i o r to t h e equivalent east alloy. S I N T E R I N G M E C H A N I S M S IN AUSTENITIC STAINLESS STEEL AND E F F E C T ON M E C H A N I C A L PROPERTIES
H. Kyogoku et al (Industrial Research Inst of Hiroshima, Fukuyama, J a p a n ) , J Japan Inst of Metals, Vol 56, No 9, 1992, 10721077. (In J a p a n e s e ) . The production of stainless steel by MIM from 9 pm powder is described. Sintering
was at 1300 to 1400:C at a pressure of 1 Pa for 0.5 to 4 hours. Image analysis was used to determine changes in porosity and grain size and it is reported t h a t the transition from pore shrinkage to growth and the coefficient of pinning force were inversely d e p e n d e n t on the grain size. Grain growth followed a cubic law a n d t h e t e n s i l e s t r e n g t h of t h e s i n t e r e d c o m p a c t was linearly related to the porosity. The prool stress conformed with the Hall-Petch relationship. C A R B U R I Z A T I O N OF A U S T E N I T E D U R I N G S I N T E R I N G O F IRONGRAPHITE POWDER COMPACTS
R.Z. Vlasyuk, Poroshkovaya Metallurgiya No 3, 1992, 34-37. (In Russian). Absorption of C during sintering, in the austenitic range, of Fe-graphite m i x t u r e s was studied by h i g h t e m p e r a t u r e radiography and metallographic methods. The activity of (" in solution in Fe al different stages was determined Correlations between strength and s t r u c t u r e of the resultant steel and (' solution are established. E F F E C T S OF E L E C T R O T H E R M A L T R E A T M E N T ON S T R U C T U R E A N D FAILURE D U C T I L I T Y OF S I N T E R E D IRON
A.S. Drachinsky el al, Poroshkovaya Metal lurgiya, No 3, 1992, 89-91, (In Russian). The fracture toughness, K~(., of sintered steel was studied within regard to the effects of alloy element distribution and porosity. It is shown t h a t an electrothermal t r e a t m e n t e l i m i n a t e s an a n o m a l o u s reduction, i t is s h o w n that a,~ e l e c t r o t h e r m a l t r e a t m e n t e l i m i n a t e s an a n o m a l o u s reduction in K~¢ which was attributed to segregation of alloy elements at grain boundaried. /Mr increase in K~,. after aging is reported aml this is attributed to t h e n u m b e r a n d d i s t r i b u t i n n of dislocations. HOT S T A M P I N G OF C O P P E R - S T E E L S
S.G. Napara-Volgina, Po,oshkovaya Metal lurgiya, No 4, 1992, 25-28. (In Russian) An i n v e s t i g a t i o n of t h e e f f e c t s (,i p r o d u c t i o n c o n d i t i o n s on p r o p e r t i e s of h o t - s t a m p e d steel c o m p o n e n t s containing 2.5 to 8% Cu is described. It is shown tha! the properties var3 wilh process parameters. Particular attention is given to the alloy with 5% Cu and the effects ol %C in the range 0.2 to 0.3%. It is shown that the strength can reach 900 ~o 1050 MPa with l0 to 12% elongation. I N C R E A S E IN C,O R R O S I O N R E S I S T A N C E BY D I F F U S I O N P L A T I N G OF C H R O M I U M ON P O R O U S IRON
I.S. Litmanovich a n d
YM. Zolotovitsky,
Poroshkovaya Metallurqiya, No 4, 1992, 28-31. (In Russian).