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Ma Qia - One of the best experts on this subject based on the ideXlab platform.

  • Metal Injection Moulding of surgical tools biomaterials and medical devices a review
    Powder Technology, 2020
    Co-Authors: Ali Dehghanmanshadi, Matthew S. Dargusch, Ma Qia, D H Stjoh
    Abstract:

    Over the last three decades, Metal Injection Moulding (MIM) has become an increasingly important manufacturing technology for small (typical maximum dimension ≤60 mm) but intricate components, including medical devices, implants and surgical tools. In particular, its ability to economically produce high volumes of precision net-shaped parts has placed it as an ideal and premier manufacturing technique for a broad range of surgical devices, orthopaedic implants and other biomedical products. This review discusses the suitability of the MIM technology from the perspectives of both design and manufacture for the fabrication of medical devices using a variety of biocompatible materials including stainless steels, titanium alloys, iron and magnesium alloys. Recent progresses in the application of the MIM technology in the medical sector and challenges are reviewed and discussed. Future trends are suggested. It is concluded that MIM is better positioned today for wider application in the biomedical sector due to the benefits of reduced powder price and easy and fast supply of intricate dies brought by Metal additive manufacturing (AM).

  • porous titanium scaffolds fabricated by Metal Injection Moulding for biomedical applications
    Materials, 2018
    Co-Authors: Ali Dehghanmanshadi, Matthew S. Dargusch, Yunhui Che, Zhiming Shi, M J Ermingham, D H Stjoh, Ma Qia
    Abstract:

    Biocompatible titaniumscaffoldswith up to 40%interconnected porosityweremanufactured through the Metal Injection Moulding process and the space holder technique. The mechanical properties of the manufactured scaffold showed a high level of compatibility with those of the cortical human bone. Sintering at 1250 °C produced scaffolds with 36% porosity and more than 90% interconnected pores, a compressive yield stress of 220 MPa and a Young's modulus of 7.80 GPa, all suitable for bone tissue engineering. Increasing the sintering temperature to 1300 °C increased the Young's modulus to 22.0 GPa due to reduced porosity, while reducing the sintering temperature to 1150 °C lowered the yield stress to 120 MPa, indicative of insufficient sintering. Electrochemical studies revealed that samples sintered at 1150 °C have a higher corrosion rate compared with those at a sintering temperature of 1250 °C. Overall, it was concluded that sintering at 1250 °C yielded the most desirable results.

  • Porous Titanium Scaffolds Fabricated by Metal Injection Moulding for Biomedical Applications
    MDPI AG, 2018
    Co-Authors: A. Dehghan-manshadi, Matthew S. Dargusch, Yunhui Che, Zhiming Shi, M J Ermingham, D H Stjoh, Ma Qia
    Abstract:

    Biocompatible titanium scaffolds with up to 40% interconnected porosity were manufactured through the Metal Injection Moulding process and the space holder technique. The mechanical properties of the manufactured scaffold showed a high level of compatibility with those of the cortical human bone. Sintering at 1250 °C produced scaffolds with 36% porosity and more than 90% interconnected pores, a compressive yield stress of 220 MPa and a Young’s modulus of 7.80 GPa, all suitable for bone tissue engineering. Increasing the sintering temperature to 1300 °C increased the Young’s modulus to 22.0 GPa due to reduced porosity, while reducing the sintering temperature to 1150 °C lowered the yield stress to 120 MPa, indicative of insufficient sintering. Electrochemical studies revealed that samples sintered at 1150 °C have a higher corrosion rate compared with those at a sintering temperature of 1250 °C. Overall, it was concluded that sintering at 1250 °C yielded the most desirable results

  • Metal Injection Moulding of non spherical titanium powders processing microstructure and mechanical properties
    Journal of Manufacturing Processes, 2018
    Co-Authors: Ali Dehghanmanshadi, Matthew S. Dargusch, Ma Qia, Yunhui Che, D H Stjoh
    Abstract:

    © 2017 The Society of Manufacturing Engineers The critical processing parameters for Metal Injection Moulding (MIM) of titanium using inexpensive non-spherical hydride-dehydride (HDH) powders with an average particle size of 45 μm were established through a series of laboratory scale Injection Moulding investigations. A slow heating rate of 1.0 K/min during thermal de-binding and sintering resulted in samples with negligible or limited distortion and nearly uniform shrinkage in all directions. Sintering at 1250 °C for 120 min was identified to be a suitable condition for MIM of HDH Ti, which produced samples with a relative density of 96.5%, uniform shrinkage of 13.9% along the length direction and 14.7% along the thickness direction. The as-sintered samples achieved a tensile strength of 395 MPa and elongation of 12.5%. The promising tensile elongation indicates that MIM of HDH titanium powder can cope with the relatively high oxygen level in the initial inexpensive HDH Ti powder as well as the unavoidable further increase in oxygen level during the MIM cycle.

  • titanium carbide precipitation in ti 22nb alloy fabricated by Metal Injection Moulding
    Powder Metallurgy, 2014
    Co-Authors: Dapeng Zhao, Thomas Ebel, Ma Qia, Keke Chang, Regine Willumei, Floria Pyczak
    Abstract:

    Metal Injection Moulding was applied to fabricate Ti–22Nb alloy as a low modulus material for biomedical applications. Tensile test specimens were Injection moulded, followed by debinding and sintering. Sintering was at 1500°C for 4 h under vacuum (10–3 Pa). Selected as-sintered Ti–22Nb samples were hot isostatically pressed at 915°C/100 MPa for 2 h. The nature of the titanium carbide precipitates in the as-sintered Ti–22Nb alloy was investigated. Selected area electron diffraction patterns revealed that the carbides are Ti2C with a fcc structure. The calculation of the phase diagram showed a significant decrease of carbon solubility in Ti–22Nb compared with that in Ti from 500 to 1500 °C, contributing to the carbide precipitation in Ti–22Nb. Due to the carbide precipitation, the as-hipped Ti–22Nb alloy exhibited higher tensile strength but lower elongation than conventionally processed Ti–22Nb.

Thomas Ebel - One of the best experts on this subject based on the ideXlab platform.

  • powder Metal Injection Moulding and heat treatment of az81 mg alloy
    Journal of Materials Processing Technology, 2019
    Co-Authors: J. G. Schaper, Martin Wolff, Thomas Ebel, Bjorn Wiese, Regine Willumeitromer
    Abstract:

    Abstract Ongoing research has proven that Mg alloys can be introduced into the Metal Injection Moulding process for the production of small parts in high quantities and of complex shape for medical as well as lightweight applications. Previously, development studies have been conducted using Mg and Mg-Ca alloys intended for medical application. However, progress towards the implementation of a process for technical and lightweight applications alloys with higher strength is needed. Therefore, in this study processing of conventional AZ81 alloy by MIM was successfully developed. Using this alloy, a yield strength of approximately 120 MPa and an ultimate tensile strength of approximately 255 MPa with elongation at fracture of approximately 7% was achieved. T4 heat treatment at 420 °C for 10 h does not reveal a positive influence on the mechanical properties this could be caused by an observed grain growth effect. This is in contrast to conventional material for example as cast, where T4 heat treatment is known to improve the mechanical properties especially elongation at fracture.

  • carbide evolution and its potential reduction methods in ti 22nb based alloys prepared by Metal Injection Moulding
    Materials Letters, 2017
    Co-Authors: Xia Luo, Thomas Ebel, Floria Pyczak, Wolfgang Limberg
    Abstract:

    Abstract Carbide evolution was investigated in order to find methods to reduce the carbide precipitation because it lowers the ductility of Metal Injection moulded -Ti alloys. Comparing Ti-22Nb and Ti-22Nb-2/10Zr alloys, the crystal structure of carbides is unchanged, but the lattice parameter of -Ti increases, then carbide fraction slightly decreases. Dissolution of carbides occurs fast around -transus temperature via short circuit diffusion but it becomes slow with decreasing temperature because of uniform atomic detachment. Based on these results, a multiple step treatment was proposed which in conjunction with grain refinement by adding Y/Y 2 O 3 , can significantly decrease the carbide fraction of Ti-22Nb-10Zr- x Y/Y 2 O 3 .

  • development of ti 22nb xzr using Metal Injection Moulding for biomedical applications
    Key Engineering Materials, 2016
    Co-Authors: Anok Babu Nagaram, Thomas Ebel
    Abstract:

    Research on biomaterials is connected inherently with the various aspects of materials science, chemistry, biology and medicine. Frequently used biomaterials for implants are titanium alloys because of their high corrosion resistance and biocompatible behaviour together with high strength and low density. One main characteristic property for the consideration of a potential implant material is the Young’s modulus which should correspond to that of human bone (4~30 GPa) as close as possible. β-Ti alloys exhibit currently the lowest value of typically 60 to 80GPa. β-Ti phase is stabilized with additive elements such as Mo, Ta, Hf and Nb. In particular, Ti-Nb alloys can exhibit a Young’s modulus around 50 to 60 GPa. Metal Injection Moulding (MIM) is a promising production technology because it overcomes the productivity and shape limitations of traditional powder compaction methods. However, formation of carbide precipitates at the grain boundaries deteriorating the ductile behavior of the materialhas become a challenge in MIM. Recent research using MIM on Ti-22Nb with the addition of Zr has revealed the reduction of carbide precipitates. In this study, different amounts of zirconium were added varying between 2 to 10 wt%. Samples produced with 10% Zr revealed the highest tensile strength of 840 MPa. In addition, specimens with higher zirconium content showed the highest ductility. XRD measurements revealed an increase in lattice constant effecting an increase of the carbon solubility of the Ti-matrix and, thus, a reduction of the carbide precipitation.

  • magnesium powder Injection Moulding for biomedical application
    Powder Metallurgy, 2014
    Co-Authors: Martin Wolff, J. G. Schaper, M. Dahms, Thomas Ebel, Karl Ulrich Kainer, Thomas Klassen
    Abstract:

    AbstractCurrently, commercial biodegradable implants are mainly made from degradable polymers, such as polyglycolic acid or polylactide acid (PLA). These polymer implants, produced by Injection Moulding technique, suffer from long degradation times between 18 and 36 months, poor mechanical properties and acidic degradation behaviour. On the other hand, magnesium alloys are drawing increasing interest as biodegradable medical implant material for orthopaedic applications in bone tissue; thus, a replacement of polymers by Mg would be attractive. The production of biomedical and biodegradable Mg alloy parts and implants by powder Metallurgy and Metal Injection Moulding (MIM) respectively offers the opportunity for economic manufacturing of parts with mechanical properties matching those of cortical bone tissue, as well as the provision of porous surface structures beneficial for cell ingrowth and vascularisation. Furthermore, the technique guarantees a homogenous microstructure being crucial for a predictabl...

  • titanium carbide precipitation in ti 22nb alloy fabricated by Metal Injection Moulding
    Powder Metallurgy, 2014
    Co-Authors: Dapeng Zhao, Thomas Ebel, Ma Qia, Keke Chang, Regine Willumei, Floria Pyczak
    Abstract:

    Metal Injection Moulding was applied to fabricate Ti–22Nb alloy as a low modulus material for biomedical applications. Tensile test specimens were Injection moulded, followed by debinding and sintering. Sintering was at 1500°C for 4 h under vacuum (10–3 Pa). Selected as-sintered Ti–22Nb samples were hot isostatically pressed at 915°C/100 MPa for 2 h. The nature of the titanium carbide precipitates in the as-sintered Ti–22Nb alloy was investigated. Selected area electron diffraction patterns revealed that the carbides are Ti2C with a fcc structure. The calculation of the phase diagram showed a significant decrease of carbon solubility in Ti–22Nb compared with that in Ti from 500 to 1500 °C, contributing to the carbide precipitation in Ti–22Nb. Due to the carbide precipitation, the as-hipped Ti–22Nb alloy exhibited higher tensile strength but lower elongation than conventionally processed Ti–22Nb.

Wolfgang Limberg - One of the best experts on this subject based on the ideXlab platform.

  • carbide evolution and its potential reduction methods in ti 22nb based alloys prepared by Metal Injection Moulding
    Materials Letters, 2017
    Co-Authors: Xia Luo, Thomas Ebel, Floria Pyczak, Wolfgang Limberg
    Abstract:

    Abstract Carbide evolution was investigated in order to find methods to reduce the carbide precipitation because it lowers the ductility of Metal Injection moulded -Ti alloys. Comparing Ti-22Nb and Ti-22Nb-2/10Zr alloys, the crystal structure of carbides is unchanged, but the lattice parameter of -Ti increases, then carbide fraction slightly decreases. Dissolution of carbides occurs fast around -transus temperature via short circuit diffusion but it becomes slow with decreasing temperature because of uniform atomic detachment. Based on these results, a multiple step treatment was proposed which in conjunction with grain refinement by adding Y/Y 2 O 3 , can significantly decrease the carbide fraction of Ti-22Nb-10Zr- x Y/Y 2 O 3 .

  • from titanium to magnesium processing by advanced Metal Injection Moulding
    Powder Metallurgy, 2012
    Co-Authors: Ku Kaine, Thomas Ebel, Wolfgang Limberg, F P Schimansky, Orley Milagres Ferri, Floria Pyczak, Martin Wolff
    Abstract:

    Metal Injection Moulding (MIM) is a good candidate for the economic mass production of complex shaped components. This is especially true for materials that are rather expensive and difficult to form, such as titanium alloys. However, the high affinity for interstitial elements such as oxygen and carbon presents a specific challenge with regard to powder purity, handling and sintering as well as the binder system and its removal. In this paper, three examples of the manufacture of high quality samples of advanced materials are shown in detail. These comprise an optimisation of the well known Ti–6Al–4V alloy with regard to MIM processing and fatigue resistance by adding 0·5 wt-% boron powder in order to effect a reduction in grain size. Second, the MIM processing of an interMetallic alloy Ti–45Al–5Nb–0·2B–0·2C (at-%) is intended for application in turbine engines and turbochargers. Third, the status of MIM of magnesium alloys is presented. In this case, the fabrication of biodegradable implants with adjust...

  • Metal Injection Moulding of titanium and titanium aluminides
    Key Engineering Materials, 2012
    Co-Authors: T Ebel, Wolfgang Limberg, Orley Milagres Ferri, Floria Pyczak, Michael Oehring, F P Schimansky
    Abstract:

    Metal Injection Moulding (MIM) attracts growing interest as an economic net-shape manufacturing technique for the processing of titanium and titanium alloys. Even for titanium-aluminides, intended for high-temperature applications, MIM is seen as a reasonable technique to overcome processing problems with conventional methods. In this paper, basic requirements in terms of raw materials, facilities and processing in order to produce high performance components are presented. Main focus is laid on the well-known Ti-6Al-4V alloy. It is shown that the tensile properties of specimens after MIM processing can exceed the requirements given by ASTM standards even without performing an additional HIP process. For an oxygen content ranging from 0.15 to 0.33 wt% plastic elongation yields excellent 14%. Fatigue measurements performed by means of 4-point-bending tests show that grain size is more important than residual porosity in order to achieve a high endurance limit. This is shown by addition of boron powder which refines the microstructure dramatically. The modified alloy Ti-6Al-4V-0.5B yields an endurance limit of 640 MPa compared to 450 MPa of MIM parts made from standard alloy powder. Sintered components from Ti-45Al-5Nb-0.2B-0.2C (at%) powder made by inert gas atomising (EIGA technique) and processed by MIM exhibit a residual porosity of only 0.2% and tensile properties comparable to cast material.

  • Metal Injection Moulding of gamma titanium aluminide alloy powder
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2006
    Co-Authors: Rainer Gerling, E Aust, Wolfgang Limberg, M Pfuff, F P Schimansky
    Abstract:

    Abstract Fine alloy powder with the nominal composition Ti 47Al 4(Mn,Cr,Nb,Si,B) (at%) has been produced by argon gas atomization and processed by Metal Injection Moulding. The main objective of process optimization concerned the level of the impurity pick-up and the influence of sintering atmosphere on porosity and microstructure. The evaporation of Al during sintering can be controlled by varying the gas pressure of the Ar atmosphere. Impuritiy levels around 1350 μg/g (O), 90 μg/g (N) and 350 μg/g (C) were achieved. During sintering, a near gamma microstructure with average gamma grain size around 12 μm is obtained. Tensile tests were conducted at RT using as-sintered samples and additionally HIP’ed test specimens. The results are discussed considering the properties of samples with comparable composition and microstructure manufactured by HIP of alloy powder and subsequent annealing.

  • advanced tial6nb7 bone screw implant fabricated by Metal Injection Moulding
    Advanced Engineering Materials, 2006
    Co-Authors: E Aust, Wolfgang Limberg, Rainer Gerling, Brigitte Oger, Thomas Ebel
    Abstract:

    The innovative technology of Metal Injection Moulding could be successfully applied to the titanium alloy TiA16Nb7. For this reactive material the complex processing steps such as feedstock fabrication, Injection Moulding, debinding and sintering were optimised in the frame of the development of a bone screw implant.

José M. Torralba - One of the best experts on this subject based on the ideXlab platform.

  • sintering optimisation of fe si soft magnetic materials processed by Metal Injection Moulding
    Powder Metallurgy, 2017
    Co-Authors: A Paezpavo, A Jimenezmorales, M Rodriguezarbaiza, E Carrenomorelli, José M. Torralba
    Abstract:

    ABSTRACTSoft magnetic materials are used in a wide variety of electromagnetic devices such as motors, relays and sensors. Over the years, the devices are becoming smaller. Therefore, it is essential to produce small parts without compromising the final properties. Metal Injection Moulding (MIM) is a cost-effective technique to produce small and complex soft magnetic parts with optimal mechanical and magnetic performance. These properties can be improved by maximising the sintered density and by the reduction of impurities content. These factors are strongly related to the sintering parameters. The goal of this study is to determine the influence of the sintering parameters on the final properties of iron–silicon soft magnetic alloys processed by Metal Injection Moulding. In this work, two alloys were sintered under different conditions. The effect of the sintering conditions on both mechanical and magnetic properties was evaluated.This paper is part of a special issue on the Advances in Materials and Proc...

  • powder Injection Moulding processing of small parts of complex shape
    International Journal of Microstructure and Materials Properties, 2013
    Co-Authors: José M. Torralba, Javier Ruiz Hidalgo, A Jimenezmorales
    Abstract:

    Powder Injection Moulding (PIM), Metal Injection Moulding (MIM) when is limited to Metals, is a fabrication route of parts with the final shape desired. This process combines the high capability of polymer Injection Moulding to produce complex shapes with the advantages of a powder route to process Metallic, ceramic or composites materials. The process has some limitations that comes from different technological steps involved in the production of the part (feedstock production, Injection, debinding and sintering). All of these different steps can be industrially controlled, being the PIM process a real alternative to produce complex parts in a high rate production method that can compete with many other processing methods to produce materials. In this work, we will go through the different steps of this manufacturing process, making special emphasis on the solutions provided by the powder technology group of the University Carlos III of Madrid (UC3M).

  • fabrication of bronze components by Metal Injection Moulding using powders with different particle characteristics
    Journal of Materials Processing Technology, 2009
    Co-Authors: Jose M Contreras, A Jimenezmorales, José M. Torralba
    Abstract:

    The aim of this work is to fabricate bronze components by Metal Injection Moulding (MIM) studying the possibility of changing partially or totally the gas atomised powder by water atomised ones that are cheaper than the former. In order to carry out this study, a bronze 90/10 gas atomised spherical powder (usual MIM powder <22 μm) and two water atomised irregular powders (particle size <35 μm and <140 μm) were mixed in different proportions. As received powders and their mixtures were used to fabricate feedstocks and processed by MIM to evaluate the influence of powder particle size and morphology on debinding and sintering stages. Finally, both mechanical properties hardness and maximum flexural stress were determined to characterize the sintered materials. The addition of irregular fine and coarse powders was found to affect the Moulding process, although densities and mechanical properties close to values of gas atomised one were obtained after sintering. Therefore, the use of water atomised bronze powders could be a promising way to diminish production costs in this technology.

  • Metal Injection Moulding of bronze using thermoplastic binder based on hdpe
    Powder Metallurgy, 2007
    Co-Authors: Gemma Herranz, A Varez, José M. Torralba
    Abstract:

    AbstractIn the present work, the Injection Moulding process of a Cu–10Sn bronze has been studied. Different formulations of binders based on high density polyethylene, paraffin wax and polyethylene glycol have been used. The optimisation of the Metallic load is based on torque measurements and rheological studies. The optimum powder loading was 60 vol.-%. The Moulding parameters are selected to obtain homogeneous specimens with three different geometries and without distortions. The green parts have an adequate strength for handling. The organic binder was eliminated by thermal debinding under N2/10%H2 atmosphere. The debinding process has been designed by means of thermogravimetrical analysis of binder and feedstock and considering the maximum heating rates at which the samples do not present cracks. The specimens were sintered at temperatures between 875 and 950°C in the same reducing atmosphere.

  • Metal Injection Moulding of hs12 1 5 5 high speed steel using a pw hdpe based binder
    Journal of Materials Processing Technology, 2006
    Co-Authors: L A Dobrzanski, Gemma Herranz, A Varez, G Matula, José M. Torralba
    Abstract:

    Abstract In this communication, we present the powder Injection Moulding (PIM) of HS12-1-5-5 high-speed steel parts using a wax-HDPE based binder. The Injection Moulding process of the feedstock (68 vol.% of Metal) has been optimized to obtain high quality green parts. The elimination of organic binder was carried out by thermal debinding under inert atmosphere. In order to keep carbon in the sample that could improve the sintering process, incomplete debinding were performed between 450 and 500 °C. In this study, we have studied the effect of different atmospheres on the debinding process. Debinding was performed under nitrogen and argon. The specimens were sintered at temperatures between 1200 and 1300 °C with steps of 10 °C in following mixture N 2 –10% H 2 atmosphere. The PIM parts present higher density than those obtained by conventional PM.

F P Schimansky - One of the best experts on this subject based on the ideXlab platform.

  • from titanium to magnesium processing by advanced Metal Injection Moulding
    Powder Metallurgy, 2012
    Co-Authors: Ku Kaine, Thomas Ebel, Wolfgang Limberg, F P Schimansky, Orley Milagres Ferri, Floria Pyczak, Martin Wolff
    Abstract:

    Metal Injection Moulding (MIM) is a good candidate for the economic mass production of complex shaped components. This is especially true for materials that are rather expensive and difficult to form, such as titanium alloys. However, the high affinity for interstitial elements such as oxygen and carbon presents a specific challenge with regard to powder purity, handling and sintering as well as the binder system and its removal. In this paper, three examples of the manufacture of high quality samples of advanced materials are shown in detail. These comprise an optimisation of the well known Ti–6Al–4V alloy with regard to MIM processing and fatigue resistance by adding 0·5 wt-% boron powder in order to effect a reduction in grain size. Second, the MIM processing of an interMetallic alloy Ti–45Al–5Nb–0·2B–0·2C (at-%) is intended for application in turbine engines and turbochargers. Third, the status of MIM of magnesium alloys is presented. In this case, the fabrication of biodegradable implants with adjust...

  • Metal Injection Moulding of titanium and titanium aluminides
    Key Engineering Materials, 2012
    Co-Authors: T Ebel, Wolfgang Limberg, Orley Milagres Ferri, Floria Pyczak, Michael Oehring, F P Schimansky
    Abstract:

    Metal Injection Moulding (MIM) attracts growing interest as an economic net-shape manufacturing technique for the processing of titanium and titanium alloys. Even for titanium-aluminides, intended for high-temperature applications, MIM is seen as a reasonable technique to overcome processing problems with conventional methods. In this paper, basic requirements in terms of raw materials, facilities and processing in order to produce high performance components are presented. Main focus is laid on the well-known Ti-6Al-4V alloy. It is shown that the tensile properties of specimens after MIM processing can exceed the requirements given by ASTM standards even without performing an additional HIP process. For an oxygen content ranging from 0.15 to 0.33 wt% plastic elongation yields excellent 14%. Fatigue measurements performed by means of 4-point-bending tests show that grain size is more important than residual porosity in order to achieve a high endurance limit. This is shown by addition of boron powder which refines the microstructure dramatically. The modified alloy Ti-6Al-4V-0.5B yields an endurance limit of 640 MPa compared to 450 MPa of MIM parts made from standard alloy powder. Sintered components from Ti-45Al-5Nb-0.2B-0.2C (at%) powder made by inert gas atomising (EIGA technique) and processed by MIM exhibit a residual porosity of only 0.2% and tensile properties comparable to cast material.

  • Metal Injection Moulding of gamma titanium aluminide alloy powder
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2006
    Co-Authors: Rainer Gerling, E Aust, Wolfgang Limberg, M Pfuff, F P Schimansky
    Abstract:

    Abstract Fine alloy powder with the nominal composition Ti 47Al 4(Mn,Cr,Nb,Si,B) (at%) has been produced by argon gas atomization and processed by Metal Injection Moulding. The main objective of process optimization concerned the level of the impurity pick-up and the influence of sintering atmosphere on porosity and microstructure. The evaporation of Al during sintering can be controlled by varying the gas pressure of the Ar atmosphere. Impuritiy levels around 1350 μg/g (O), 90 μg/g (N) and 350 μg/g (C) were achieved. During sintering, a near gamma microstructure with average gamma grain size around 12 μm is obtained. Tensile tests were conducted at RT using as-sintered samples and additionally HIP’ed test specimens. The results are discussed considering the properties of samples with comparable composition and microstructure manufactured by HIP of alloy powder and subsequent annealing.

  • prospects for Metal Injection Moulding using a gamma titanium aluminide based alloy powder
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2002
    Co-Authors: R Gerling, F P Schimansky
    Abstract:

    Abstract Alloy powder of an advanced gamma titanium aluminide alloy (γ-TAB: Ti–47Al–4(Mn, Nb, Cr, Si, B) (at.%)) was produced by argon gas atomization. The fine powder ( 2 : 790 μg g −1 , N 2 : 140 μg g −1 ), the sintered and HIP'ed samples are characterized by a considerable increase in O 2 and N 2 . Both types of impurities vary in the depth of the samples in the range of 1600–8000 μg g −1 (O 2 ) and 160–890 μg g −1 (N 2 ). After HIP the microstructure is of duplex type. Tensile tests at room temperature resulted in a yield strength of 410 MPa, an ultimate tensile strength of 430 MPa and a plastic elongation of 0.6%.