High Entropy Alloys for Hydrogen industry: Study of H2 Permeation Barrier effect through an electrochemical method optimized by data analysis and softcomputing

Energy transition is part of the ecological transition and hydrogen technology is considered a key enabling technology to lead society towards a decarbonized economy, through the promotion of the hydrogen chain value and its integration in the different productive processes.

One of the key factors for hydrogen to make a significant contribution to the energy transition is the need to be stored and distributed. The selection of materials to produce tanks, tubes or valves to storage and transport hydrogen relays in materials permeability to hydrogen and their susceptibility to embrittlement. The H penetrates, forms pores and generates cracks that embrittles the material with the result of fracture. Recently, High Entropy Alloys (HEA) are receiving increasing attention as a new class of potential materials to withstand contact with hydrogen.

NextHEA4H2 proposes the study of the performance of two HEA in contact with hydrogen. For this purpose, ASTM and ISO standards developed to measure permeation to hydrogen by electrochemical methods will be applied. Two steels currently used for applications in contact with hydrogen will be also tested as reference materials.

Under these standards there are a large number of experimental conditions that can affect the results of the test. On one hand experimental conditions as temperature or chemical electrolyte characteristics. On the other hand, material variables such as finishing quality of the charging and discharging surfaces, superficial residual stresses or density of crystallographic defects in the material.

Therefore, an exhaustive analysis of the experiment itself must be accomplished to understand which conditions or variables generate noise and increase the variance in the results of the tests, i.e. diffusion coefficient and solubility parameters.

To produce reliable characterization of the materials it is proposed to define and validate an advanced design of experiments based on the use of covariance information. This process allows gathering information to be analyzed by means of data multivariate analysis, enabling to find significant relations between experimental conditions and the measured variability of the results. With this finite information, mathematical models based on classical and advanced machine learning techniques can be generated. The models will allow to expand the information to the entire space of proposed options, allowing to obtain information for larger number of cases and possible significant cases within the space will be tested to validate the process.

Once the experimental procedure is optimized, the results obtained for the two HEAs and the reference steels will be deeply discussed. Particular attention will be paid to the effect of the material surface features on the diffusion coefficient and its variability and the effect on trapping-detrapping mechanisms in hydrogen solubility. This analysis will enable to design the optimal surface finishing for future coatings intended as Hydrogen Permeation Barriers.

The work team comprises experts with strong experience/skills in physical metallurgy, materials characterization and advanced techniques of data analysis. Along the project, we intend to contrast our results with end-users through the Basque Cluster of Energy (association of 180 companies which activity is related somehow to energy). This brings the necessary range of technical and end-user knowledge required to deliver our ambitious research aim.

The study of two HEAs to protect components of the hydrogen transport/storage infrastructure against hydrogen-embrittlement is performed in this study. Substitution of current steels, such as SS316L or 34CrMo4 used to manufacture oversized parts, by another steels cheaper, with higher mechanical strength and coated with a thin layer of a material with excellent Hydrogen Permeation Barrier (HPB) properties is the ambitious goal of this research work. NextHEA4H2 succeed will allow designing safer and cheaper components with longer service life for the industry of hydrogen in the upcoming energy transition. Based on this introduction, the main objective of this project is the study of the potentiality of specific HEAs to act as HPBs. This main objective requires accomplishing the following specific objectives:

  • Perform a sound, robust and reliable procedure to conduct permeation tests
  • Understand and control the variance of the experiments for any prefixed experiment conditions
  • Characterize the hydrogen permeability of the HEAs and compare with those of currently used materials
  • Observe the performance of the samples loaded with hydrogen in small punch tests and determine the formation of cracks and their propagation
  • Propose the optimal coating based in each HEA intended to act as HPB in transport and storage of hydrogen

Hydrogen Permeability

Diffusion of hydrogen atoms through the thin metal isolation membranes

Hydrogen Embrittlement

Mechanical damage of a metal due to the penetration of hydrogen

Hydrogen Storage and Transportation

Hydrogen storage can be distributed continuously in pipelines or batch wise by ships, trucks, railway or airplanes

High Entropy Alloy based coating Barriers

Alloys that are formed by mixing equal or relatively large proportions of several elements

Microstructural Characterization

Microstructure characterization can help give insight into many properties of the material

Design of Experiments

Branch of applied statistics that deals with planning, conducting, analyzing, and interpreting controlled tests

Mathematical Modelling

Process of describing a real world problem in mathematical terms, usually in the form of equations

Mathematical Optimization

Selection of a best element, with regard to some criterion, from some set of available alternatives


Design of experiments

There is a great uncertainty in the proposed characterization tests. It is proposed to analyse the problem based on a DoE that defines the process in the most complete way.

Characterization and testing

Materials must be characterized, and permeation tests will be conducted. It is necessary to properly characterize them in view of future comparison tests and for the comprehension of the physical and chemical mechanisms involved.

Modeling and optimization

Development of mathematical models and multi-objective optimization must be applied to obtain the desired properties on the characterization


The annual event of the European Federation of Corrosion (EUROCORR2023)

27–31 August 2023

Our research team within the NextHEA4H2 and H2MAT projects have attended and presented their most recent research at the international conference EUROCORR 2023 (https://www.eurocorr2023.org/) held in Brussels (Belgium) from August 27 to 31, 2023. In this event, the work “Microstructural and corrosion characterization of different types of High Entropy Alloys” was presented by Lucia Castrillejo Robles.

Materials for the hydrogen industry: Embrittlement and permeability characterization techniques in hydrogen-rich environments

8 September 2023

Within the general objectives of the H2MAT and NextHEA4H2 projects is the characterization of the susceptibility to hydrogen embrittlement of materials. In this event, different evaluation techniques will be presented and the advances in the development of the permeation test by electrochemical techniques that the different partners work on will be shared.

Successfully developed seminars

9 September 2023

The seminars “Materials for the hydrogen industry: Techniques for characterizing embrittlement and permeability in hydrogen-rich environments” held at the Bilbao Engineering School on September 8, 2023 were held with great attendance and with an interesting diffusion in relationship to the characterization of the susceptibility to hydrogen embrittlement of materials. These seminars are framed within the general objectives of the H2MAT and NextHEA4H2 projects.


Roberto Fernandez Martinez

Roberto Fernandez Martinez is Doctor in Industrial Engineering from the University of La Rioja (Spain) and currently a professor at the Department of Electrical Engineering at the University of the Basque Country (Spain). His research work is focused on modeling and
optimizing industrial processes and products. To this end, he works by implementing data mining techniques, spatial data mining, soft computing and machine learning systems to solve real problems in the industrial sector, in the area of materials science and in the electrical engineering sector. This research task is reflected in the 25 research projects (regional, national and European) in which he has collaborated, in the 58 indexed scientific articles published, in the more than 70 conferences (national and international) attended, in the 12 book chapters and in the three published books, and in the two patents generated.

Teresa Guraya Diez

Professor Teresa Guraya received her graduation of Chemistry in 1984 and her Master of Chemistry in 1985 from the University of the Basque Country, before completing her Master of Metallurgy in 1989 and PhD research in 1995 at the Universidad de Navarra. She then spent two years in the private company Construcción y Auxiliar de Ferrocarril CAF S.A. (1995-1997). During that period, she worked in the areas of design and structural calculation of railroad structures. On her return to academia in 1998, Teresa Guraya joined the Department of Mining and Metallurgical Engineering and Materials Science at University of the Basque Country. Today, she teaches topics on engineering materials and manufacturing technologies/processes at School of Engineering of Bilbao. She combines her research activity with a fully commitment with teaching innovation and education for sustainability. In 2020 she was appointed as member of the panel of the Spanish Society of Materials.

Ana Okariz Larrea

Professor Ana Okariz was graduated in Physics in 1991 and got her PhD in Physics in 1997, both in the UPV/EHU. Her doctoral thesis focused on the analysis of subsurface structures in opaque solids by means of photothermal techniques and was awarded a cum laude qualification and the UPV/EHU doctoral prize. She has been lecturer at the UPV/EHU from 1993 to the present day, initially as an associate lecturer, and later as a Senior Lecturer (1998).

Since She joined the UPV/EHU, she have participated in numerous research projects, initially in the Photothermal Techniques group and later in the eMERG group, both in the Bilbao School of Engineering of the UPV/EHU. As a result of this participation, She have assist to various national and international conferences and published the research results in prestigious journals in their respective areas, almost all of them included in the JCR.

Pedro José Jimbert Lacha

Pello made his Phd Thesis in Tecnalia and presented it in Mondragon Unibertsitatea (MU) in 2009. During this period Pello worked in the Manufacturing department studying different metal manufacturing processes like hot forging, sheet metal forming and high speed forming. Pello main research interest was related with the different processes characterization parameters and the relations with the final mechanical and microstructural properties obtained for different metallic alloys.

Currently his research focuses on the study of the processing parameters of different metallic materials (forging, rolling, casting, sheet forming) to optimize them and thus improve the final quality and properties of the products. Characterization of the microstructure on a micro and nano scale and experimental measurement of the physical-chemical and mechanical properties of these metallic materials.

Lorea Armendariz Martinez

Lorea Armendariz Martinez graduated in Physics from the University of the Basque Country in 2021 and earned a Master’s Degree in Advanced Materials Engineering from the Bilbao School of Engineering. She conducted her degree thesis on advanced laser processing of materials at the Ceit Research Center and is currently employed as a researcher in the Department of Mining and Metallurgical Engineering and Materials Science (UPV). Since the beginning of her MSc thesis, she has focused on understanding hydrogen-metal interactions in high entropy alloys for the hydrogen industry.

Lucia Castrillejo Robles

Lucía Castrillejo, a Materials Engineer from the Technical University of Madrid, UPM (2021) and holder of a Master in New Materials from University of the Basque Country, UPV/EHU (2022). She is currently a predoctoral student in the «Department of Mining and Metallurgical Engineering and Materials Science» at UPV/EHU. Her research journey began at CENIM (CSIC), focusing on the corrosion and biomedical behavior of alloys with a graphene film. During her MSc project at the Consorcio de Aguas Bilbao-Bizkaia, CABB, Lucía conducted corrosion analysis of metals, revealing her commitment to practical applications.

Now immersed in her Ph.D. thesis, Lucía is dedicated to modeling hydrogen interaction and diffusion within the lattice structures of different metals, with a specific focus on High-Entropy Alloys. Her research aims to find practical industrial applications for these alloys, bridging the gap between academic exploration and real-world implementation in the landscape of energy and hydrogen technologies.

Yoana Bilbao Zarraga


Roberto Fernandez Martinez
Faculty of Engineering Bilbao
University of The Basque Country (UPV/EHU)
Engineer Torres Quevedo Square 1
48013 Bilbao
web: https://emerg.es/
email: emerg@nexthea4h2.com
Tel: (+34) 946014191

eMERG Materials Engineering Research Group

eMERG (emerg.es) is a multidisciplinary applied research group on materials of technological interest. eMERG is focused on the design, study and optimization of metal alloys with high added value. The fields of application that eMERG is currently looking at are in the energy and health sectors.

To process the alloys eMERG work with advanced manufacturing technologies, additives, semi-solid forming or coating application technologies. In the optimization phase eMERG use computational techniques that significantly reduce the experimental need.

Faculty of Engineering Bilbao

The Faculty of Engineering in Bilbao School was born on January 5, 2016, as a result of a reorganization process of faculties and schools within the University of the Basque Country. This new university center brings together the facilities, staff, students and qualifications that until then were divided into 4 schools, some of them centuries old.

The School is made up of around 4,750 students, more than 550 professionals from the teaching staff, more than 150 from the administration and services staff, in addition to more than 130 from the research staff.

Grant TED2021-130757A-I00 funded by MCIN/AEI/ 10.13039/501100011033 and by the “European Union NextGenerationEU/PRTR”

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