Periodic Reporting for period 1 - CoCoMag (Multi-property Compositionally Complex Magnets for Advanced Energy Applications)
Reporting period: 2023-06-01 to 2024-05-31
Considering the effects of global warming and impact of fossil fuels, a rapid and sustainable transition towards renewable energy sources and energy conversion systems is essential, which includes specifically the often overlooked but very important technology sector cooling. However, this transition comes with challenges, particularly in the increased demand for critical metals like rare earth (RE) elements and cobalt. Green energy technologies such as e-mobility, wind turbines, and magnetic refrigeration require these metals. For the green energy transition, magnets play a critical role in achieving net-zero emissions by enhancing the efficiency of energy conversion systems. In addition, traditional gas-compression cooling methods have seen only small efficiency improvements over the past century and are far from being considered as “green”. Magnetic refrigeration offers a more efficient alternative, also by avoiding high global warming potential (GWP) refrigerants, but the use of critical metals is indeed an issue.
The CoCoMag project addresses the challenge of a sustainable future by focusing on two primary applications: e-mobility and magnetic refrigeration. Our innovative approach involves the new design concept for magnetic materials using the compositionally complex alloys (CCAs) approach, in our case based on hexagonal Fe2P- and MM'X-type compounds. These CCA-designed alloys will ultimately eliminate or minimize the use of critical elements, providing a more sustainable solution for both permanent magnets and magnetocaloric materials.
By leveraging the extensive compositional flexibility of CCAs, we can go beyond traditional alloying methods that have been used ever since the Bronze Age. The CCA approach allows us to address both the primary magnetic properties and equally important secondary engineering properties such as mechanical and chemical stability. Our methodology integrates theoretical predictions, machine learning and experimental validation to accelerate the alloy design process.
Successful implementation of the CoCoMag project will contribute significantly to the decarbonization and electrification of the mobility and refrigeration sectors. By developing new magnets free of critical elements, we aim to address the challenges posed by the increasing demand for critical metals and support the broader adoption of green energy technologies. This project not only promises technological advancements but also aligns with strategic goals of sustainability and resource efficiency, thereby setting the stage for impactful outcomes in the green energy sectors.
The CoCoMag project addresses the challenge of a sustainable future by focusing on two primary applications: e-mobility and magnetic refrigeration. Our innovative approach involves the new design concept for magnetic materials using the compositionally complex alloys (CCAs) approach, in our case based on hexagonal Fe2P- and MM'X-type compounds. These CCA-designed alloys will ultimately eliminate or minimize the use of critical elements, providing a more sustainable solution for both permanent magnets and magnetocaloric materials.
By leveraging the extensive compositional flexibility of CCAs, we can go beyond traditional alloying methods that have been used ever since the Bronze Age. The CCA approach allows us to address both the primary magnetic properties and equally important secondary engineering properties such as mechanical and chemical stability. Our methodology integrates theoretical predictions, machine learning and experimental validation to accelerate the alloy design process.
Successful implementation of the CoCoMag project will contribute significantly to the decarbonization and electrification of the mobility and refrigeration sectors. By developing new magnets free of critical elements, we aim to address the challenges posed by the increasing demand for critical metals and support the broader adoption of green energy technologies. This project not only promises technological advancements but also aligns with strategic goals of sustainability and resource efficiency, thereby setting the stage for impactful outcomes in the green energy sectors.
We have performed computational screening of more than 2,000 initial alloy compositions using density functional theory (DFT), CALPHAD modeling, and an active machine learning (ML) framework. These screening results include significant advances in MM'X-type and Fe2P-type magnetocaloric and permanent magnet materials. Theory suggested Mn-Ni-Fe-Si compositions for phase stability and magnetic distortion, while ML suggested Al doping, leading to promising compositions for the selected applications. For Fe2P-type magnetocaloric materials, theory suggested compositions with Mn/Fe ratios close to one, and substitution of P with Si and B increased the magnetic entropy change. For MM'X-type permanent magnets, various Fe-Ga and Fe,Co-Mn-B compositions were identified as promising materials due to their predicted high magnetization. For Fe2P-type permanent magnets, high anisotropy (1.5 MJ/m³) for (Fe,Co)2(P,Si)) was predicted by substituting Fe with Co and P with Si, with ongoing efforts to avoid or minimize Co while maintaining the magnetic properties.
Experimental synthesis and validation have confirmed the computational predictions. Key results include the successful synthesis of Mn-Ni-Si systems with Fe and Cu substitutions in MM'X-type magnetocaloric materials, achieving desired properties at room temperature. For Fe2P-type magnetocaloric materials, we have synthesized (Mn,Fe)2(P,Si,B)-type compounds, optimizing the Mn/Fe ratio and significantly reducing the thermal hysteresis with boron doping. Discovery of potential hard magnetic phases in MM’X permanent magnets is achieved. Optimum composition balanced with microstructural refinement of Fe2P permanent magnets is also achieved.
Experimental synthesis and validation have confirmed the computational predictions. Key results include the successful synthesis of Mn-Ni-Si systems with Fe and Cu substitutions in MM'X-type magnetocaloric materials, achieving desired properties at room temperature. For Fe2P-type magnetocaloric materials, we have synthesized (Mn,Fe)2(P,Si,B)-type compounds, optimizing the Mn/Fe ratio and significantly reducing the thermal hysteresis with boron doping. Discovery of potential hard magnetic phases in MM’X permanent magnets is achieved. Optimum composition balanced with microstructural refinement of Fe2P permanent magnets is also achieved.
Our project has made significant advances beyond the current state of the art in alloy design by screening compositionally complex alloys using computational methods such as density functional theory (DFT), thermodynamic phase diagram modeling (CALPHAD). We have predicted promising material systems using DFT and CALPHAD modeling and confirmed the predictions experimentally on both polycrystalline and single crystalline samples. This theoretical-experimental handshake is extended to an active machine learning (ML) framework. The iterative feedback between experimental results and simulations will further refine alloy compositions and ensure progress in the development of high-performance magnetic materials with significant economic, environmental and social impact.