Skip to main content

Virtual Design, Virtual Processing and Virtual Testing of Metallic Materials

Periodic Reporting for period 4 - VIRMETAL (Virtual Design, Virtual Processing and Virtual Testing of Metallic Materials)

Reporting period: 2020-05-01 to 2021-02-28

Materials innovations have been at the core of most of the major disruptive technologies, and Materials Science and Engineering can be considered as a transversal discipline which encompasses the progress in all areas of technology. Broadly speaking, the interaction between materials and technology has followed one of these patterns: either the synthesis of a material with novel properties led to a technological breakthrough (i.e. gigantic magnetoresistance), or current engineering materials were introduced and slowly improved for novel applications following a trial-and-error strategy (i.e. composites in aerospace). Both circumstances act as limiting factors of technological progress, particularly nowadays when engineering design tools have radically reduced the time necessary to optimize new products. The ability to design new materials or optimise actual ones in silico for engineering applications will reduce dramatically the time necessary to introduce new materials in the market and will also incorporate materials into the design optimisation process of new components. Both scenarios will reduce dramatically the time necessary to reach the market for many disruptive technologies.

Within this context, the objective of the VIRMETAL project was to demonstrate that it is possible to predict the microstructure and mechanical properties of metallic alloys using a cascade of modelling strategies covering different length and time scales. So new metallic alloys can be designed, tested and optimized before they are actually manufactured in the laboratory. The focus of the project was on materials engineering i.e. understanding how the structure of the materials develops during processing (virtual processing), the relationship between this structure and the properties (virtual testing) and how to select materials for a given application (virtual design).
The project was focused in two types of alloys (Al and Mg) of very large industrial interest. The activities of the project were structured along two parallel pillars, namely virtual processing and virtual testing. The first achievement of the VIRMETAL project was to establish a cascade of modelling tools to predict the microstructure of cast Al-Cu alloys beginning by first principles simulations. The microstructural predictions were validated in all cases with ad hoc experiments and they were also extended to Mg alloys. The second achievement was to predict the critical resolved shear stress for dislocation motion in Al-Cu, Mg-Al and Mg-Zn alloys with different precipitates through the application of another cascade of modelling tools. Moreover, the experimental validation of the critical resolved shear stress for dislocation motion and twin nucleation and growth in single crystals of different Al and Mg alloys was achieved by means of nanomechanical testing techniques, which provided a novel strategy to obtain the bulk properties of metals as a function of composition and temperature. Finally, the mechanical properties (strength, fatigue life) of polycrystals were obtained by means of crystal plasticity models and computational homogenization of representative volume elements of the microstructure.

In addition, the expertise acquired within the project in alloy design has been used to design and manufacture new metallic alloys by selective laser melting and the micro- and nano-mechanical testing techniques developed during the project have been used to assess the mechanical properties of novel metal/ceramic and metal/metal nanolaminates, particularly at high temperature.

From the viewpoint of knowledge transfer, the research project VIRMETAL has led -so far- to > 50 publications in international peer-reviewed journals (including Science, Acta Materialia, Journal of the Mechanics and Physics of Solids, Nano Letters, etc) and four doctoral theses. Moreover, another three doctoral theses are very much advanced and will be defended by the end of 2021 or beginning of 2022. The scientific results of the research project have been disseminated through 50 plenary/keynote lectures in international conferences and 42 seminars, delivered as a result of invitations by universities and research centers throughout the world. Moreover, technology transfer of the results has been mainly accomplished through the license of CAPSUL- Crystal Plasticity simulation, a software package developed by J. Segurado, J. LLorca, V. Herrera-Solaz, A. Cruzado, S. Lucarini, S. Hauoala with support from the VIRMETAL project. The software is registered and has been licensed to MSC Software Belgium in 2019. CAPSUL is included in Digimat, the platform for materials simulation of e-Xstream engineering, a division of MSC Software Belgium S. A.
The main scientific challenge of the project was to develop multiscale modeling strategies using a bottom-up, hierarchical approach. Thus, modeling efforts began with ab initio simulations of the behavior of materials and bridging of the length and time scales, and multiscale modeling had to be accomplished through the transfer of information between different modeling strategies. These linking of modelling tools to go from atoms to components has been fully accomplished in some cases, such as the modelling of precipitation hardening in Al-Cu alloys and partially in the case of Mg alloys. The strategies developed and validated in the project open the way to the in silico design of metallic alloys for structural applications.

New experimental data were necessary for the calibration and validation of models, particularly at the nm-µm-mm level and the project has developed new characterization techniques to measure the mechanical properties of bulk metallic alloys from micromechanical tests. These goals were accomplished through a high-throughput strategy based on diffusion-couples and micropillar compression tests. This novel strategy opens the possibility for fast, high-throughput experimental characterization of the strength of new metallic alloys, which will help to reduce the development time of new alloys.

The need to understand the deformation mechanisms of metallic alloys at the nm-µm length scale has led to the development of in situ mechanical tests within the scanning and transmission electron microscopes including tests at high temperature. These novel experimental tools have allowed to unravel the deformation mechanisms of metallic nanolaminates and opened the path to elastic strain engineering, a novel strategy to modify the electronic properties of materials through the application of elastic strains. This strategy may lead to breakthroughs to discover materials with unprecedented physico-chemical properties (LLorca, Science, 360 (6386), 264, 2018).
Multiscale modelling strategy for virtual processing and virtual testing of the project VIRMETAL