- Email: [email protected]
Mössbauer effect study of phases in mechanically alloyed iron-zinc
PM
control of grain size and led to improved understanding of the relationships between abrasion resistance, hardness, %Co and grain size. CUTTING P E R F O R M A N C E OF HYPERFUNCTIONAL CERAMICS
Y.Miyamoto e t al. (Osaka University, Osaka, Japan.) J. Jpn. Soc. P o w d e r P o w d e r Metal[, Vol 42, No 12, 1995, 1389-1393. (In Japanese.) AI203-TiC tools are noted to be brittle when used to cut cast iron. It is reported that tools with graded coatings had been prepared by high temperature synthesis and HIP. The coated tools are shown to have improved fracture resistance which is attributed to residual compressive stress in the coatings. P R O P E R T I E S OF POWDER METALLURGY H I G H S P E E D S T E E L S
S.Stolarz et al. (Inst. Metali Niezelaznych, Glwice, Poland.) Metal. Proszkow, No 2, 1996, 23-33. (In Polish.) Structures and properties of T15, T42, M3-2 and M35 high speed steels, pressed, sintered and heat treated, are described. Results of cutting performance tests are presented. MICROSTRUCTURE AND RUPTURE S T R E N G T H O F T U N G S T E N CARBIDENICKEL-COBALT H.Ping. (Central South University of Technology, Changsha, China.) P M Technol., Vol 14, No 4, 1996, 287-290. (In Chinese.) It is reported t h a t during quality inspection of industrial production the rupture strengths and microstructures of WC-Co-Ni alloys had been investigated using electron optics techniques. The factors affecting reduction of rupture strength are discussed. F O R M A T I O N OF FINE GRAINED S T R U C T U R E S ON FRICTION SURFACE OF TITANIUM CARBIDE CERAMICS
V.F.Britun, Y.G.Tkachenko. Poroshkovaya Metall., No 3/4, 1996, 84-88. (In Russian.) Fragmentation of TiC in surface layers of TiC based materials was investigated by electron microscopy. Two types of structure were found. The first is associated with plastic deformation and the second with sintering of wear debris into the surface.
Intermetallic materials SYNTHESIS O F R U T H E N I U M A L U M I N I D E BY REACTIVE POWDER PROCESSING
I.M.Wolff. (MINTEK, Randburg, South Africa.) Metal1. Mater. Trans..4, Vol 27A, No 11, 1996, 3688-3699.
LITERATURE
REVIEW
Structure, properties and processing of RuA1 are d i s c u s s e d w i t h r e g a r d to structural applications. PM is considered to be a viable method of production. It is reported that reactive HIP allows ',Tnthesis of homogeneous high density material. Process parameters are outlined. It is noted that non-equilibrium phase,~ may be formed, which require heat treatment to complete the synthesis. Part production is shown to be feasible. COMPACTION AND CHARACTERIZATION O F MECHANICALLY ALLOYED TITANIUM ALUMINIDES
F.H.Froes e t al. (University of Idaho, Moscow, Idaho, USA.) Metall. Mater. Trans. ,4, Vol 28A, No 2, 1997, 293-302. An investigation of the effects of mechanical alloying on elemental Ti24at%Al-11%Nb and Ti-55%A1 mixtures a n d p r e a l l o y e d A1-24%AI-11%Nb is described. After 10 hours milling the TiA1-Nb powder contained the B2, body c e n t r e d cubic, phase, and the Ti-AI showed some amorphization. The prealloyed Ti-AI-Nb powder contained B2 phase and fine grain size. Milled powders were consolidated by HIP, pseudo-HIP and dynamic methods. The ternary alloys contained B2 and an orthorhombic phase. The TtA1 contained 2/riA1 and ~2TiaAl. Grain size was r e d u c e d by dynamic compaction. E F F E C T O F HIP T E M P E R A T U R E ON STRUCTURE A N D P R O P E R T I E S O F CARBIDE D I S P E R S E D A L U M I N I D E S
M.Hashii e t al. (Ritsumeikan University, Shiga, Japan.) J. J a p a n Inst. Metals, Vol 60, No 10, 1996, 944-951. (In Japanese.) It is reported that Ti-48at%Al-l%Mn had been mechanically alloyed in the presence of nC6H6 and consolidated by HIP at 900, 1100 and 1300°C to a fine equiaxed duplex structure of 7TiA1 and TiaAIC, grain sizes being 185 nm, 510 nm and 1.5 tim respectively. Higher tempertures increased grain size and formed some a2 phase. Mechanical p r o p e r t i e s were determined and related to structures. MICROSTRUCTURAL CONTROL OF A TITANIUM ALUMINIDE ALLOY Y.Tomota et al. (Ibaraki University, Ibarakiken, Japan.) J. J p n Inst. Metals, Vol 60, No 10, 1996, 1007-1012. (In Japanese.) Structures and mechanical properties of hot-extruded elemental Ti-AI-Mn powders during reactive sintering were investigated with the objective of HIP processing below 1380°C. Material HIPed at 560 or 700°C increased in density on heat treatment and was readily deformed at 1000°C. This process route is shown to allow control of microstructure.
l
Mechanical alloying M O S S B A U E R E F F E C T STUDY OF P H A S E S IN MECHANICALLY ALLOYED IRON-ZINC
Z.Liu, O.N.C.Uwakweh. (University of Cincinnati, Cincinnati, USA.) Metall. Mater. Trans. A, Vol 28A, No 3A, 1997, 743-747. Mechanical alloying and aging of elemental Fe-Zn powders were investigated. The synthesis of FeaZnlo and Fe5Zn21 was monitored by Mbssbauer spectroscopy. The measurements suggest that these are similar metastable states and that separate transformation routes may lead to distinct crystal structures. MICROSTRUCTURE AND NANOSCALE C O M P O S I T I O N OF MEC,HANICALLY ALLOYED IRON-COPPER J.Y.Huang e t aL (Chinese Academy of Sciences, Shenyang, China.) A e t a Mater., Vol 45, No 1, 1997, 113-124. The s t r u c t u r e s and c o m p o s i t i o n distribution of mechanically alloyed Cu-16 at %Fe and Fe-40 at %Cu 'were investigated by e l e c t r o n microscopy. D e f o r m a t i o n twinning was observed in Cu-16%Fe. In F e - 4 0 % C u shear bands and n a n o c r y s t a l s were detected. In both materials grain size was small before m i l l i n g , w h i c h is s h o w n t o be a prerequisite for dissolution of Fe in Cu. In Cu-16%Fe grain centre and boundary compositions were close to average but there was much inhomogeneity. Two stages in MA process are identified, an initial reduction in grain size to a steady value, later deformation being accommodated in boundaries.
1996 WORLD C O N G R E S S ON POWD E R METALLURGY. T h e f o l l o w i n g A b s t r a c t s are f r o m p a p e r s w h i c h w e r e p r e s e n t e d at t h e C o n g r e s s , w h i c h w a s h e l d i n W a s h i n g t o n DC, U S A , i n J u n e 1996.
Surface treatments PLASMA N I T R I D I N G O F H I G H STRENGTH SINTERED STEEL
I.Kuhn e t al. (Federal University of St. Catherine, Brazil.) An investigation of plasma nitriding of sintered high strength low alloy steels was described. The object wm to evaluate the effects of process conditions, nitriding time and nitriding atmosphere. Surfaces were characterized. The effect of e x t e n t of homogenization during sintering was also assessed.
MPR October 1997 39
control of grain size and led to improved understanding of the relationships between abrasion resistance, hardness, %Co and grain size. CUTTING P E R F O R M A N C E OF HYPERFUNCTIONAL CERAMICS
Y.Miyamoto e t al. (Osaka University, Osaka, Japan.) J. Jpn. Soc. P o w d e r P o w d e r Metal[, Vol 42, No 12, 1995, 1389-1393. (In Japanese.) AI203-TiC tools are noted to be brittle when used to cut cast iron. It is reported that tools with graded coatings had been prepared by high temperature synthesis and HIP. The coated tools are shown to have improved fracture resistance which is attributed to residual compressive stress in the coatings. P R O P E R T I E S OF POWDER METALLURGY H I G H S P E E D S T E E L S
S.Stolarz et al. (Inst. Metali Niezelaznych, Glwice, Poland.) Metal. Proszkow, No 2, 1996, 23-33. (In Polish.) Structures and properties of T15, T42, M3-2 and M35 high speed steels, pressed, sintered and heat treated, are described. Results of cutting performance tests are presented. MICROSTRUCTURE AND RUPTURE S T R E N G T H O F T U N G S T E N CARBIDENICKEL-COBALT H.Ping. (Central South University of Technology, Changsha, China.) P M Technol., Vol 14, No 4, 1996, 287-290. (In Chinese.) It is reported t h a t during quality inspection of industrial production the rupture strengths and microstructures of WC-Co-Ni alloys had been investigated using electron optics techniques. The factors affecting reduction of rupture strength are discussed. F O R M A T I O N OF FINE GRAINED S T R U C T U R E S ON FRICTION SURFACE OF TITANIUM CARBIDE CERAMICS
V.F.Britun, Y.G.Tkachenko. Poroshkovaya Metall., No 3/4, 1996, 84-88. (In Russian.) Fragmentation of TiC in surface layers of TiC based materials was investigated by electron microscopy. Two types of structure were found. The first is associated with plastic deformation and the second with sintering of wear debris into the surface.
Intermetallic materials SYNTHESIS O F R U T H E N I U M A L U M I N I D E BY REACTIVE POWDER PROCESSING
I.M.Wolff. (MINTEK, Randburg, South Africa.) Metal1. Mater. Trans..4, Vol 27A, No 11, 1996, 3688-3699.
LITERATURE
REVIEW
Structure, properties and processing of RuA1 are d i s c u s s e d w i t h r e g a r d to structural applications. PM is considered to be a viable method of production. It is reported that reactive HIP allows ',Tnthesis of homogeneous high density material. Process parameters are outlined. It is noted that non-equilibrium phase,~ may be formed, which require heat treatment to complete the synthesis. Part production is shown to be feasible. COMPACTION AND CHARACTERIZATION O F MECHANICALLY ALLOYED TITANIUM ALUMINIDES
F.H.Froes e t al. (University of Idaho, Moscow, Idaho, USA.) Metall. Mater. Trans. ,4, Vol 28A, No 2, 1997, 293-302. An investigation of the effects of mechanical alloying on elemental Ti24at%Al-11%Nb and Ti-55%A1 mixtures a n d p r e a l l o y e d A1-24%AI-11%Nb is described. After 10 hours milling the TiA1-Nb powder contained the B2, body c e n t r e d cubic, phase, and the Ti-AI showed some amorphization. The prealloyed Ti-AI-Nb powder contained B2 phase and fine grain size. Milled powders were consolidated by HIP, pseudo-HIP and dynamic methods. The ternary alloys contained B2 and an orthorhombic phase. The TtA1 contained 2/riA1 and ~2TiaAl. Grain size was r e d u c e d by dynamic compaction. E F F E C T O F HIP T E M P E R A T U R E ON STRUCTURE A N D P R O P E R T I E S O F CARBIDE D I S P E R S E D A L U M I N I D E S
M.Hashii e t al. (Ritsumeikan University, Shiga, Japan.) J. J a p a n Inst. Metals, Vol 60, No 10, 1996, 944-951. (In Japanese.) It is reported that Ti-48at%Al-l%Mn had been mechanically alloyed in the presence of nC6H6 and consolidated by HIP at 900, 1100 and 1300°C to a fine equiaxed duplex structure of 7TiA1 and TiaAIC, grain sizes being 185 nm, 510 nm and 1.5 tim respectively. Higher tempertures increased grain size and formed some a2 phase. Mechanical p r o p e r t i e s were determined and related to structures. MICROSTRUCTURAL CONTROL OF A TITANIUM ALUMINIDE ALLOY Y.Tomota et al. (Ibaraki University, Ibarakiken, Japan.) J. J p n Inst. Metals, Vol 60, No 10, 1996, 1007-1012. (In Japanese.) Structures and mechanical properties of hot-extruded elemental Ti-AI-Mn powders during reactive sintering were investigated with the objective of HIP processing below 1380°C. Material HIPed at 560 or 700°C increased in density on heat treatment and was readily deformed at 1000°C. This process route is shown to allow control of microstructure.
l
Mechanical alloying M O S S B A U E R E F F E C T STUDY OF P H A S E S IN MECHANICALLY ALLOYED IRON-ZINC
Z.Liu, O.N.C.Uwakweh. (University of Cincinnati, Cincinnati, USA.) Metall. Mater. Trans. A, Vol 28A, No 3A, 1997, 743-747. Mechanical alloying and aging of elemental Fe-Zn powders were investigated. The synthesis of FeaZnlo and Fe5Zn21 was monitored by Mbssbauer spectroscopy. The measurements suggest that these are similar metastable states and that separate transformation routes may lead to distinct crystal structures. MICROSTRUCTURE AND NANOSCALE C O M P O S I T I O N OF MEC,HANICALLY ALLOYED IRON-COPPER J.Y.Huang e t aL (Chinese Academy of Sciences, Shenyang, China.) A e t a Mater., Vol 45, No 1, 1997, 113-124. The s t r u c t u r e s and c o m p o s i t i o n distribution of mechanically alloyed Cu-16 at %Fe and Fe-40 at %Cu 'were investigated by e l e c t r o n microscopy. D e f o r m a t i o n twinning was observed in Cu-16%Fe. In F e - 4 0 % C u shear bands and n a n o c r y s t a l s were detected. In both materials grain size was small before m i l l i n g , w h i c h is s h o w n t o be a prerequisite for dissolution of Fe in Cu. In Cu-16%Fe grain centre and boundary compositions were close to average but there was much inhomogeneity. Two stages in MA process are identified, an initial reduction in grain size to a steady value, later deformation being accommodated in boundaries.
1996 WORLD C O N G R E S S ON POWD E R METALLURGY. T h e f o l l o w i n g A b s t r a c t s are f r o m p a p e r s w h i c h w e r e p r e s e n t e d at t h e C o n g r e s s , w h i c h w a s h e l d i n W a s h i n g t o n DC, U S A , i n J u n e 1996.
Surface treatments PLASMA N I T R I D I N G O F H I G H STRENGTH SINTERED STEEL
I.Kuhn e t al. (Federal University of St. Catherine, Brazil.) An investigation of plasma nitriding of sintered high strength low alloy steels was described. The object wm to evaluate the effects of process conditions, nitriding time and nitriding atmosphere. Surfaces were characterized. The effect of e x t e n t of homogenization during sintering was also assessed.
MPR October 1997 39