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New possibilities for metal ceramic composite friction materials for railway disc brakes
Mechanical alloying AMORPHIZATION IN MECHANICALLY ALLOYED ZIRCONIUM-ZINC ALLOYS B. Zhang et al (Hunan University, Hunan, China) J. Physics Condensed Matter, Vol 5, No 7, 1993, L85-L90. It is reported that the alloy Zn-40at%Zr had been amorphized by high energy ball milling. Structure and thermal stability were determined. It is reported that the energy of formation of Zr-Zn bonds provides the driving force for amorphization. The activation energy for subsequent crystallization is reported to be 3.068 eV. PHASE FORMATION AND MARTENSITC TRANSFORMATION IN MECHANICALLY ALLOYED IRON-NICKEL ALLOYS C. Kuhrt, L. Schultz (Siemens AG, Erlagen, Germany) J. Applied Physics, Vol 73, No 4, 1993, 1975-1980. It is reported that a non-equilibrium phase diagram for mechanically alloyed FeNi alloys has been established. Phases were Fe rich body centred cubic and Ni rich face centered cubic. Maximum solubilties were 30at%Ni in Fe and 4O%Fe in Ni which decrease slightly for increased milling intensity. Grain size was about 25 nm. Magnetic properties are reported. Phase transformations differ from cast/wrought alloys. The non-equilibrium structure is shown to hinder formation of Fe-Ni martensite.
Refractory metals and alloys PROTECTION OF NIOBIUM AND TANTALUM ALLOYS AGAINST HIGH TEMPERATURE OXIDATION P. Riidammer et al (Metallwerk Plansee, Reutte, Austria) Znt. J. Refractory Metals & Hard Materials, Vol 12, No 5, 1993-1994, 283-293. The use of coatings to protect Ta and Nb alloys against oxidation is discussed with regard to applications at high temperatures. Silicides, noble metals, and Sic multilayer systems, applied in a variety of ways, are described. Cyclic oxidation tests at 1450°C and 5 Pa with the coatings characterized at all stages. It is reported that Si-BO’%;Cr-BO%Fe coatings on Nb-lO%W2.5%Zr and Ta-lO%W substrates gave the best results. ELECTRON BEAM FLOATING ZONE MELTING OF REFRACTORY METALS AND ALLOYS
predicted dislocation structures. Application to W and MO alloys is discussed. Use was made of X-ray divergent beam techniques in the study. SURFACE INVESTIGATIONS OF REFRACTORY METALS WITH FIELD ION MICROSCOPY WITH ATOM PROBE E. Krautz (Technical University of Graz, Graz, Austria) Znt. J. Refractory Metals & Hard Materials, Vol 12, No 5, 1993-1994, 315-324. The use of the field ion microscope with atom probe is described for use in surface investigations of refractory metals. It is reported that the technique allows a three dimensional reconstruction of the desorbed volume and direct observation of alloy components and nano-precipitates. PM
components
VALVE SEAT INSERT MATERIALS FOR INTERNAL COMBUSTION ENGINES T. Wolicka, Z. Opiekun (Polytechnic Rzeszowska, Rzeszow, Poland) Metal. Proszkow, Vol 25, No 1, 1994, 19-27. (In Polish). The composition and structural features of a range of materials for inlet and exhaust valve seats for internal combustion engines are revioewed. The alloys considered were newly developed PM materials, cast steel and cast iron. NEW POSSIBILITIES FOR METAL CERAMIC COMPOSITE FRICTION MATERIALS FOR RAILWAY DISC BRAKES R. Reznicek, D. Cizec (Pramet AS, Sumperk, Czechoslovakia.) Pokroky Psaskove Metalurgie, No 1, 1994, 4-13. (In Czech). The use of metal-ceramic composites in railway disc brakes is discussed and the short life of cast iron discs is noted. The sintering on to cast iron discs of a wear resistant surface is proposed. Tests on the coated discs, under dry and lubricated conditions, are described. The potential of the proceedure is outlined. PRESS TOOLS FOR THE PRODUCTION OF ARTICLES FROM POWDER S.M. Vaitsekhovich, Poroshkovaya Metallurgiya, No 8, 1993, 98-103. (In Russian). The manufacture of large parts from powder is discussed. It is shown to be possible to make a part and to remove it from the die in one operating cycle by making use of frictional forces. Close attention is given to tool design.
G. Glebovsb, V.N. Semenov (Inst. of Solid State Physics, Moscow, Russia) Znt. J. Refiactorg
Metals & Hard Materials,
Vol 12, No 5, 1993-1994, 295-301. It is reported that electron beam melting floating zone techniques had been employed to puri& refractory metals and to produce single and bi-crystals with 40
MPR April 1995
PM’94 The abstracts which follow are of papers which were presented at the 1994 Powder Metallurgy World Congress which was held in Paris, France from 6th to 9th June 1994.
Steel PRODUCTION OF MICRO-ALLOYED STEELS BY MEANS OF POWDER METALLURGY P. Brunel et al (Sintertech, Pont de Claix, France) Investigations to establish the effects of Nb, V and Cr additions on low C sintered steels were described. The compositions were chosen to correspond with microalloyed high strength low alloy steels. Two powders, prealloyed and elemental mixtures, were used. The sintered steels were hardened and tempered at 650°C to give an increase in tensile strength of 450 MPa. FORMATION OF INTERMEDIATE PHASES AND EFFECTS ON SINTERED IRON-SILICON-TITANIUM ALLOYS K Pischang (Dresden University of Technology, Dresden, Germany) A study of Fe-5wt%Sii3%Ti with and without lO%Ni and 0.8%C was described. precipitation hardening was investigated and the ternary phase FelzTilBSils was detected. Structure and properties were described and discussed. DIMENSIONAL CONTROL OF HIGH STRENGTH PM COPPER STEELS Y.T. Chen, R. Kiefer (Pitney Bowes lnc, Shelton, Connecticut, USA) Dimensional change during sintering of Cu high strength steels was discussed growth being attributed to swelling of Cu. Control of swelling, by use of zoned atmosphere, was reviewed. Account was taken of formation of martensite and retained austenite. Dimensional control through tempering was demonstrated. SINTERING AND MICROSTRUCTURES OF PM VALVE SEAT INSERT MATERIALS H. Danninger et al (Technical University Vienna, Vienna, Austria) The ability of sintered valve seat insert materials, for use in internal combustion engines, to withstand wear, was discussed. A study of valve seat alloys was described. Microstructures, wear behaviour and process parameters were correlated. EFFECT OF BORON ADDITIONS ON PROPERTIES OF LOW ALLOY MANGANESE-CHROMIUMMOLYBDENUM STEELS E. Dudrova et al (Slovak Academy of Sciences, Kosice, Slovakia) An investigation of the effect of 0.2 to 0.6%B on sintering, structure and properties of 1.56%Cr-0.7%Mn-0.2%Mo steels, with and without C, was described. It was reported that B enhances sintering and gives beneficial changes in microstructure. A dual phase structure evolved in presence of C.
Refractory metals and alloys PROTECTION OF NIOBIUM AND TANTALUM ALLOYS AGAINST HIGH TEMPERATURE OXIDATION P. Riidammer et al (Metallwerk Plansee, Reutte, Austria) Znt. J. Refractory Metals & Hard Materials, Vol 12, No 5, 1993-1994, 283-293. The use of coatings to protect Ta and Nb alloys against oxidation is discussed with regard to applications at high temperatures. Silicides, noble metals, and Sic multilayer systems, applied in a variety of ways, are described. Cyclic oxidation tests at 1450°C and 5 Pa with the coatings characterized at all stages. It is reported that Si-BO’%;Cr-BO%Fe coatings on Nb-lO%W2.5%Zr and Ta-lO%W substrates gave the best results. ELECTRON BEAM FLOATING ZONE MELTING OF REFRACTORY METALS AND ALLOYS
predicted dislocation structures. Application to W and MO alloys is discussed. Use was made of X-ray divergent beam techniques in the study. SURFACE INVESTIGATIONS OF REFRACTORY METALS WITH FIELD ION MICROSCOPY WITH ATOM PROBE E. Krautz (Technical University of Graz, Graz, Austria) Znt. J. Refractory Metals & Hard Materials, Vol 12, No 5, 1993-1994, 315-324. The use of the field ion microscope with atom probe is described for use in surface investigations of refractory metals. It is reported that the technique allows a three dimensional reconstruction of the desorbed volume and direct observation of alloy components and nano-precipitates. PM
components
VALVE SEAT INSERT MATERIALS FOR INTERNAL COMBUSTION ENGINES T. Wolicka, Z. Opiekun (Polytechnic Rzeszowska, Rzeszow, Poland) Metal. Proszkow, Vol 25, No 1, 1994, 19-27. (In Polish). The composition and structural features of a range of materials for inlet and exhaust valve seats for internal combustion engines are revioewed. The alloys considered were newly developed PM materials, cast steel and cast iron. NEW POSSIBILITIES FOR METAL CERAMIC COMPOSITE FRICTION MATERIALS FOR RAILWAY DISC BRAKES R. Reznicek, D. Cizec (Pramet AS, Sumperk, Czechoslovakia.) Pokroky Psaskove Metalurgie, No 1, 1994, 4-13. (In Czech). The use of metal-ceramic composites in railway disc brakes is discussed and the short life of cast iron discs is noted. The sintering on to cast iron discs of a wear resistant surface is proposed. Tests on the coated discs, under dry and lubricated conditions, are described. The potential of the proceedure is outlined. PRESS TOOLS FOR THE PRODUCTION OF ARTICLES FROM POWDER S.M. Vaitsekhovich, Poroshkovaya Metallurgiya, No 8, 1993, 98-103. (In Russian). The manufacture of large parts from powder is discussed. It is shown to be possible to make a part and to remove it from the die in one operating cycle by making use of frictional forces. Close attention is given to tool design.
G. Glebovsb, V.N. Semenov (Inst. of Solid State Physics, Moscow, Russia) Znt. J. Refiactorg
Metals & Hard Materials,
Vol 12, No 5, 1993-1994, 295-301. It is reported that electron beam melting floating zone techniques had been employed to puri& refractory metals and to produce single and bi-crystals with 40
MPR April 1995
PM’94 The abstracts which follow are of papers which were presented at the 1994 Powder Metallurgy World Congress which was held in Paris, France from 6th to 9th June 1994.
Steel PRODUCTION OF MICRO-ALLOYED STEELS BY MEANS OF POWDER METALLURGY P. Brunel et al (Sintertech, Pont de Claix, France) Investigations to establish the effects of Nb, V and Cr additions on low C sintered steels were described. The compositions were chosen to correspond with microalloyed high strength low alloy steels. Two powders, prealloyed and elemental mixtures, were used. The sintered steels were hardened and tempered at 650°C to give an increase in tensile strength of 450 MPa. FORMATION OF INTERMEDIATE PHASES AND EFFECTS ON SINTERED IRON-SILICON-TITANIUM ALLOYS K Pischang (Dresden University of Technology, Dresden, Germany) A study of Fe-5wt%Sii3%Ti with and without lO%Ni and 0.8%C was described. precipitation hardening was investigated and the ternary phase FelzTilBSils was detected. Structure and properties were described and discussed. DIMENSIONAL CONTROL OF HIGH STRENGTH PM COPPER STEELS Y.T. Chen, R. Kiefer (Pitney Bowes lnc, Shelton, Connecticut, USA) Dimensional change during sintering of Cu high strength steels was discussed growth being attributed to swelling of Cu. Control of swelling, by use of zoned atmosphere, was reviewed. Account was taken of formation of martensite and retained austenite. Dimensional control through tempering was demonstrated. SINTERING AND MICROSTRUCTURES OF PM VALVE SEAT INSERT MATERIALS H. Danninger et al (Technical University Vienna, Vienna, Austria) The ability of sintered valve seat insert materials, for use in internal combustion engines, to withstand wear, was discussed. A study of valve seat alloys was described. Microstructures, wear behaviour and process parameters were correlated. EFFECT OF BORON ADDITIONS ON PROPERTIES OF LOW ALLOY MANGANESE-CHROMIUMMOLYBDENUM STEELS E. Dudrova et al (Slovak Academy of Sciences, Kosice, Slovakia) An investigation of the effect of 0.2 to 0.6%B on sintering, structure and properties of 1.56%Cr-0.7%Mn-0.2%Mo steels, with and without C, was described. It was reported that B enhances sintering and gives beneficial changes in microstructure. A dual phase structure evolved in presence of C.