- Email: [email protected]
Effects of injection moulding conditions on structure and properties of titanium alloy
had been directly nitrided in situ. The directly nitrided alloys showed higher strength. This is attributed to better bonding between Al and ALN. The alloys had low coefficient of friction under lubricated conditions. This is shown to be due to micro-grooving which helped to retain oil films.
PM aluminium base alloys K.KIein et al. (University of Hanover, Hanover, Germany.) Pokroky Prask. Metal., Vol37, No 4, 1999, 19-28. (In Czech.)
An investigation of microstructure of Al27%?+6%Ni alloys made from rapidly solidified powder, to determine the effects of powder particle size, is described. X-ray diffraction scanning and transmission electron microscopy were used in the study.
Chromium Mechanical properties of high purity chromium C.L.Briantetnl. (Brown b&&y, Provklence, USA.) hr. J. Refract. Mer&/Hard Mater., Vol 18, No I, 21X0, 9-1 I. The mechanical properties of Cr were investigated. It is reported that a high interstitial content leads to brittle fracture above ambient tempertures, C being particularly damaging. A single Cr crystal showed notch ductility at room temperature which was retained after recrystallization to a polycrystal.
Iron and steel Prediction of fatigue life of sintered steels E.S.Palma, A.Cngnonil (Uniuersiry of Minus Gerais, Belo Htizonte, Brazil.) Powder Me&l., Vol42, No 4, 1999, 320-324.
Fatigue damage in sintered 1.75%Cu-OS%C steel was investigated experimentally and the results were compared with a model. Both stress and strain controlled experiments were performed. The experimental fatigue life was less than predicted, the difference increasing with increase in porosity.
Improvement of iron compact green strength by powder surface modification G.Pkiner et al. (National Research Council of Canada, Ottawa, Cam&J PowderMetal., Vol42, No4, 1999, 325-330.
Green strength of powder compacts was studied and the factors contributing to green strength are identified. The effects on green strength of powder surface modification were investigated. Compacts were pressed from powder which had been treated with dilute ulphuric acid and plated with Cu by a non-catalytic displacement method. The surface modification is reported to influence green strength.
36
MPR
Februarv 2001
Mechanical alloying of iron-aluminium
R.M.Gennan. (Pennsylvania State University, USA.) lnt. J. Powder Metall., Vol25, No 4, 1999, 57-67.
M.Hashii. (Municipal Industrial Research Inst., Nagoya, Japan.) J. Jpn Sot. Powder/Powder Metal., Vol46, No 10, 1999, 1079-1084. (InJapanese.)
Processing of tool steels by injection moulding is discussed. It is noted that sintering without distortion may be difficult. MIM of M2 tool steel was computer simulated with consideration of densification, distortion and microstructural coarsening. Some densification occurs in the solid state but liquid phase sintering is essential for full densification. In the liq uid state, liquid films spread along grain boundaries and there is rapid grain growth. This is incorporated in the simulation to determine optimum sintering conditions. A time-temperature window, 1255 “C for 30 minutes, for 0.85%C is given. Temperature is reduced as %C increases.
Elemental Fe-25at%Al powders were mechanically alloyed and the structures characterized. X-ray diffraction showed weakening of Fe and Al reflections. After 30 minutes a supersaturated Fe-Al solid solution was formed with fine FeAl, particles. Particle size was 5 to 20 pm. Annealing after mechanical alloying produced FeAIj and aFe.
Titanium Effects of injection moulding conditions on structure and properties of titanium alloy M.Takita et al. (Nagoya Uniuersay, Nagoya, Japan.) J. .Jpn Sot. Powder/Powder Metal., Vol46, No 10, 1999, 1053-1057. (InJapanese.)
It is reported that Ti-6%Al-4%V alloys had been made by injection moulding to determine effects of process conditions on structure and properties. Sintering at 950 “C gave above 96% density. %0 increased with sintering time. A t‘ensile strength of 950 MPa was attained, comparable with cast alloys. Crack initiation was at coarse a sites in the structure.
Mechanical alloying in hydrogen and consolidation of titanium-aluminium A.Takasakl. (Shibaura Inst. of Technology, Omiya, Japan.) J. Jpn Sot. Powder/Powdpr Metall., Vol46, No 10, 1999, 1085-1089. (Injapanese.)
Elemental Ti-(28,43 and 52)at%Al powders were mechanically alloyed in H for 30 hours, cold isostatically pressed and vacuum sintered. Densities and hardness were compared with materials made from powders mechanically alloyed in Ar and from mixed powders. The H is reported to enhance solid state reactions and amorphization without hydrides forming and to give higher densities.
Fabrication of titanium-nickel shape memory alloy by injection moulding University, H.Kyogoku, S.Komarsu. (Kinki Higashihiroshima, lapan.) J. Jpn Sot. Powder/Powder Metall., Vol46, No 10, 1999, 1103.1107. (InJapanese.)
TiNi shape memory alloys were fabricated from gas atomized Ti and carbonyl Ni powders by metal injection moulding. Process conditions are described. The materials were characterized for structure, density and shape memory properties.
Powder injection moulding Computer model for sintering densification of injection moulded tool steel
Metal injection moulding of nano structured tungsten-copper powders I.H.Moon et al. (Hanyang University, Seoul, Korea.)
ht. J. Powder Metal., Vol25, No 4, 1999,47-55. Nanostructured W-Cu powder was mechanically milled and injection moulded, with a wax-polymer-stearic acid binder, in as-milled and as-milled and thermally reduced conditions. The debinding cycle gave good surface finish, shape retention and complete debinding which was followed by isostatic repressing and sintering to densities above 96% for both powders types. Densification is attributed to W grain growth and particle rearrangement.
Crystallization and properties of paraffin wax-polymer blend J.K.Kim, B K.Kim. (Pohang University of Science ad Technology, Pohang, Korea.) J. Jpn Sot. Powder/Pow&r Metall., Vol46, No 8, 1999, 823-829. (In English.) The effects of liquid/liquid phase separation on crystallization and mechanical properties of a paraffin wax-poly( ethylene-vinyl acetate) polymer binder blend were investigated by differential scanning calorimetry. Above 100 “C there was a single liquid solution, which separated into two fractions on cooling between 100 “C and 90 “C. Crystallization increased with increased holding time between 100 “C and 90 “C. The maximum flexural modulus occurred at 35% of the polymer.
Evaluation of the accuracy of rheological data for injection moulding feedstocks B.O.Rhee, S.H.Lee. (Ajou University, &won, Korea.) J.JpnSoc. PowderlPowderMetall., Vol46, No8, 1999, 830-836. (In English.)
Three corrections needed to ensure accuracy, in characterization of PIM feedstocks by capillary rheometry, are named as Rabinowitsch, Bagley and Morley. It is noted that these may not be applied in practice. These are analysed in terms of a range of factors using two stainless steel powders, spherical
www.metal-oowder.net
PM aluminium base alloys K.KIein et al. (University of Hanover, Hanover, Germany.) Pokroky Prask. Metal., Vol37, No 4, 1999, 19-28. (In Czech.)
An investigation of microstructure of Al27%?+6%Ni alloys made from rapidly solidified powder, to determine the effects of powder particle size, is described. X-ray diffraction scanning and transmission electron microscopy were used in the study.
Chromium Mechanical properties of high purity chromium C.L.Briantetnl. (Brown b&&y, Provklence, USA.) hr. J. Refract. Mer&/Hard Mater., Vol 18, No I, 21X0, 9-1 I. The mechanical properties of Cr were investigated. It is reported that a high interstitial content leads to brittle fracture above ambient tempertures, C being particularly damaging. A single Cr crystal showed notch ductility at room temperature which was retained after recrystallization to a polycrystal.
Iron and steel Prediction of fatigue life of sintered steels E.S.Palma, A.Cngnonil (Uniuersiry of Minus Gerais, Belo Htizonte, Brazil.) Powder Me&l., Vol42, No 4, 1999, 320-324.
Fatigue damage in sintered 1.75%Cu-OS%C steel was investigated experimentally and the results were compared with a model. Both stress and strain controlled experiments were performed. The experimental fatigue life was less than predicted, the difference increasing with increase in porosity.
Improvement of iron compact green strength by powder surface modification G.Pkiner et al. (National Research Council of Canada, Ottawa, Cam&J PowderMetal., Vol42, No4, 1999, 325-330.
Green strength of powder compacts was studied and the factors contributing to green strength are identified. The effects on green strength of powder surface modification were investigated. Compacts were pressed from powder which had been treated with dilute ulphuric acid and plated with Cu by a non-catalytic displacement method. The surface modification is reported to influence green strength.
36
MPR
Februarv 2001
Mechanical alloying of iron-aluminium
R.M.Gennan. (Pennsylvania State University, USA.) lnt. J. Powder Metall., Vol25, No 4, 1999, 57-67.
M.Hashii. (Municipal Industrial Research Inst., Nagoya, Japan.) J. Jpn Sot. Powder/Powder Metal., Vol46, No 10, 1999, 1079-1084. (InJapanese.)
Processing of tool steels by injection moulding is discussed. It is noted that sintering without distortion may be difficult. MIM of M2 tool steel was computer simulated with consideration of densification, distortion and microstructural coarsening. Some densification occurs in the solid state but liquid phase sintering is essential for full densification. In the liq uid state, liquid films spread along grain boundaries and there is rapid grain growth. This is incorporated in the simulation to determine optimum sintering conditions. A time-temperature window, 1255 “C for 30 minutes, for 0.85%C is given. Temperature is reduced as %C increases.
Elemental Fe-25at%Al powders were mechanically alloyed and the structures characterized. X-ray diffraction showed weakening of Fe and Al reflections. After 30 minutes a supersaturated Fe-Al solid solution was formed with fine FeAl, particles. Particle size was 5 to 20 pm. Annealing after mechanical alloying produced FeAIj and aFe.
Titanium Effects of injection moulding conditions on structure and properties of titanium alloy M.Takita et al. (Nagoya Uniuersay, Nagoya, Japan.) J. .Jpn Sot. Powder/Powder Metal., Vol46, No 10, 1999, 1053-1057. (InJapanese.)
It is reported that Ti-6%Al-4%V alloys had been made by injection moulding to determine effects of process conditions on structure and properties. Sintering at 950 “C gave above 96% density. %0 increased with sintering time. A t‘ensile strength of 950 MPa was attained, comparable with cast alloys. Crack initiation was at coarse a sites in the structure.
Mechanical alloying in hydrogen and consolidation of titanium-aluminium A.Takasakl. (Shibaura Inst. of Technology, Omiya, Japan.) J. Jpn Sot. Powder/Powdpr Metall., Vol46, No 10, 1999, 1085-1089. (Injapanese.)
Elemental Ti-(28,43 and 52)at%Al powders were mechanically alloyed in H for 30 hours, cold isostatically pressed and vacuum sintered. Densities and hardness were compared with materials made from powders mechanically alloyed in Ar and from mixed powders. The H is reported to enhance solid state reactions and amorphization without hydrides forming and to give higher densities.
Fabrication of titanium-nickel shape memory alloy by injection moulding University, H.Kyogoku, S.Komarsu. (Kinki Higashihiroshima, lapan.) J. Jpn Sot. Powder/Powder Metall., Vol46, No 10, 1999, 1103.1107. (InJapanese.)
TiNi shape memory alloys were fabricated from gas atomized Ti and carbonyl Ni powders by metal injection moulding. Process conditions are described. The materials were characterized for structure, density and shape memory properties.
Powder injection moulding Computer model for sintering densification of injection moulded tool steel
Metal injection moulding of nano structured tungsten-copper powders I.H.Moon et al. (Hanyang University, Seoul, Korea.)
ht. J. Powder Metal., Vol25, No 4, 1999,47-55. Nanostructured W-Cu powder was mechanically milled and injection moulded, with a wax-polymer-stearic acid binder, in as-milled and as-milled and thermally reduced conditions. The debinding cycle gave good surface finish, shape retention and complete debinding which was followed by isostatic repressing and sintering to densities above 96% for both powders types. Densification is attributed to W grain growth and particle rearrangement.
Crystallization and properties of paraffin wax-polymer blend J.K.Kim, B K.Kim. (Pohang University of Science ad Technology, Pohang, Korea.) J. Jpn Sot. Powder/Pow&r Metall., Vol46, No 8, 1999, 823-829. (In English.) The effects of liquid/liquid phase separation on crystallization and mechanical properties of a paraffin wax-poly( ethylene-vinyl acetate) polymer binder blend were investigated by differential scanning calorimetry. Above 100 “C there was a single liquid solution, which separated into two fractions on cooling between 100 “C and 90 “C. Crystallization increased with increased holding time between 100 “C and 90 “C. The maximum flexural modulus occurred at 35% of the polymer.
Evaluation of the accuracy of rheological data for injection moulding feedstocks B.O.Rhee, S.H.Lee. (Ajou University, &won, Korea.) J.JpnSoc. PowderlPowderMetall., Vol46, No8, 1999, 830-836. (In English.)
Three corrections needed to ensure accuracy, in characterization of PIM feedstocks by capillary rheometry, are named as Rabinowitsch, Bagley and Morley. It is noted that these may not be applied in practice. These are analysed in terms of a range of factors using two stainless steel powders, spherical
www.metal-oowder.net