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- Salmasi, Armin, 1983-, et al.
(författare)
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Geometry effects during sintering of graded cemented carbides: Modelling of microstructural evolution and mechanical properties
- 2019
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Ingår i: Results in Materials. - : Elsevier BV. - 2590-048X. ; 1
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Tidskriftsartikel (refereegranskat)abstract
- Cemented carbides with mesoscopically non-homogeneous properties by design represent a potential to enhanceperformance in metal cutting and rock drilling. Development of in-homogeneous structured hard materialsthrough an ICME approach requires a thorough understanding of diffusion kinetics during solid and liquid statesintering. In this work, we used thermodynamics and diffusion kinetics modelling tools to predict the micro-structure and resulting properties of cemented carbide composites. First, we designed and gradient sintered two(WC-TiCN-Co) cemented carbides with different nitrogen to titanium ratios. Second, we reproduced the experi-mental results in 2D by means of thermodynamic and kinetic simulations. In the last step we calculated fracturetoughness KIC, and Vickers hardness of cemented carbides. The agreement between simulations and experimentalresults is fair and acceptable
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| 2. |
- Salmasi, Armin, 1983-
(författare)
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ICME guided study of mass transport in production and application of cemented carbides
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cemented carbides are metallic composites consisting of a WC hard phase and a ductile binder, usually Co-based, produced by powder metallurgy and sintering. Cemented carbides are an essential part of modern material and manufacturing processes. However, Co powder is classified as a carcinogenic material with serious health hazards, and most virgin Co reservoirs are located in conflict regions. In addition, there are monopolies in the market for pure tungsten. Therefore, reducing the consumption of cobalt or replacing it with other non-hazardous elements would increase the sustainability of cemented carbide production. Furthermore, advances in production technology can help overcome raw material limitations. One such advancement is non-homogeneous structures and properties for optimization of microstructure which is the topic of this thesis. Integrated computational materials engineering (ICME) and its complementary tools, calculation of phase diagram (CALPHAD), and ab-initio modeling are strong tools that bridge experimentation and modeling. In this thesis, a framework for the material design of non-homogeneous cemented carbides is proposed and tested using these computational tools. The workflow of the material design of non-homogeneous microstructure and properties were studied on different length scales. Atomistic modeling with density functional theory (DFT), ab-initio molecular dynamics (AIMD), and generalized hydrodynamics (GHD) were used to model the viscosity of liquid Co binder. In addition, the mobility of Ti and Fe in disordered BCC TiFe alloy was assessed using new experimental data from the diffusion couple experiments and an electron probe micro-analyzer (EPMA). These two studies were conducted to complete the data necessary to study cemented carbides’ processing and performance. The other studied phenomenon studied by experimentation and modeling is the formation of the gradient zone and the γ cone structure. In addition, a phenomenological model for liquid phase migration (LPM) was created and implemented using the homogenization approach. The LPM pro- cess was studied experimentally and modeled with the YAPFI software. A study of these performers was necessary to link processing and microstructure. On the performance side, the chemical interaction between cutting tools and Ti alloys was studied in detail through experimentation and modeling of diffusion. In addition, hardness and toughness models were applied to predict the longevity of studied cemented carbides. Finally, by applying ICME and material design, a high entropy alloy (HEA) alternative to Co binder was designed, produced, and tested. The research presented in this dissertation attempts to fill the gaps in the material design workflow of cemented carbides by developing new tools and methods based on ICME and CALPHAD paradigms. This goal is achieved by studying different length scales, processing methods, microstructure, properties, and performance of cemented carbides.
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