Interface investigations of cosintered parts produced via two component metal injection moulding (2CMIM) require a high demand of experiments. To reduce the experimental time and effort, the commercial simulation software DICTRA-Thermo-Calc was used to predict the interface formation. In this work, the material combination 316L/17-4PH is examined at different sintering temperatures: 1270 and 1360 degrees C, and three holding times: 1, 2 and 4 h at 1360 degrees C. Micrographs, energy dispersive X-ray/scanning electron microscopy linescans and simulations showed the evolution of the interfaces for different conditions. The broadest diffusion layer was obtained at 1360 degrees C for 4 h. At an elevated temperature, the interdiffusion provoked the formation of a rich ferrite region close to the interface in the 17-4PH, which was increased for longer holding times. The simulation was able to predict the same tendencies obtained by experimental results
In this study different powder metallurgical processing routes, commonly used for refractory metal based materials, were evaluated on their impact on mechanical properties of a multi-component Nb-20Si-23Ti-6Al-3Cr-4Hf (at.%) alloy. Powder was produced by gas-atomization or high energy mechanical alloying of elemental powders and then consolidated either by HIPing or powder injection molding (PIM). The PIM process requires fine particles. In this investigation powder batches of gas-atomized powder (< 25 µm) and mechanically alloyed powder (< 25 µm) were compacted via PIM. Fine (< 25 µm) and coarser (106-225 µm) particle fractions of gas-atomized powder were compacted via HIPing for comparison. Quantitative analysis of the resulting microstructures regarding porosity, phase formation, phase distribution, and grain size was carried out in order to correlate them with the ensuing mechanical properties such as compressive strength at various temperatures
Refractory metal silicide composites on the basis of Nb ss -Nb 5 Si 3 have been investigated as potential alternatives for nickel-base superalloys for years because of their low densities and good high-temperature strengths. NbSibased composites are typically produced by arc-melting or casting. Samples in this study, however, were produced by powder metallurgy because of the potential for near net-shape component fabrication with very homogeneous microstructures. Either gas atomized powder or high-energy mechanically alloyed elemental powders were compacted by powder injection molding or hot isostatic pressing. Heat treatments were applied for phase stability evaluation. Slight compositional changes (oxygen, nitrogen, or iron) introduced by the processing route, i.e., powder production and consolidation, can affect phase formations and phase transitions during the process. Special focus is put on the distinction between different silicides (Nb 5 Si 3 and Nb 3 Si) and silicide modifications (a-, b-, and c-Nb 5 Si 3 ), respectively. These were evaluated by x-ray diffraction and energy-dispersive spectroscopy measurements with the additional inclusion of thermodynamic calculations using the calculated phase diagram method.
Two-component metal injection moulding (2C-MIM) allows producing functionally graded metal parts of complex shape by co-sintering. Until now several studies have demonstrated that different material properties can be combined. Another promising material combination is titanium and iron-based materials. It can combine the biocompatibility and low density of titanium with a ductile and cost efficient stainless steel. However, co-sintering these materials reveals challenges due to a significant mismatch in sintering shrinkage and limitations in sintering temperature for both materials. The recent study showed that Ti-6Al-4V can be joined to the stainless steel 316L by 2C-MIM provided that certain constraints are taken in account. The quality of the interface before and after co-sintering is a crucial factor for intact parts after processing. By applying sinterdilatometry the mismatch in shrinkage was compensated by using adjusted powder characteristics and tailored feedstock compositions. A co-sintering cycle was defined with regard to the sintering characteristics of both materials. The developed two-component specimens revealed significant interdiffusion of alloying elements at the Ti-6Al-4V / 316L interface and a tensile strength of 282 MPa after co-sintering.
The paper describes results that were achieved by joining the ferritic stainless steel AISI 430 and the austenitic stainless steel AISI 314 by two-component metal injection molding. Sinterdilatometry was used to compare the sintering response of the materials. To compensate discrepancies in shrinkage during co-sintering, several gas-atomized powder fractions were combined. Using this approach, feedstock combinations which did not exceed a shrinkage mismatch of 5% were processed into micro tensile test specimens by sequential or simultaneous co-injection molding. The ferritic/austenitic interfaces were characterized with a focus on interdiffusion of alloying elements and mechanical properties. Defect-free and well-connected bi-material specimens with magnetic/non-magnetic properties were obtained. Results showed that the interdiffusion between the utilized steels resulted in a local strengthening effect that increased the hardness and mechanical properties of the interface. The tensile strength was comparable to the strength of the base material and all specimens failed outside the interface. It demonstrates that the investigated material combination is suitable to produce magnetic/non-magnetic parts by two-component metal injection molding
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