A carregar...
Projeto de investigação
Sem título
Financiador
Autores
Publicações
Role of TiB2 inoculation particles during welding of a AlCoCrFeNi high entropy alloy
Publication . Lopes, J. G.; Candeias, A.; Agrawal, P.; Shen, J.; Schell, N.; Mishra, R. S.; Oliveira, J. P.; DEMI - Departamento de Engenharia Mecânica e Industrial; UNIDEMI - Unidade de Investigação e Desenvolvimento em Engenharia Mecânica e Industrial; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); DCM - Departamento de Ciência dos Materiais; Elsevier
High entropy alloys (HEAs) are a novel class of materials that represent an evolution of common engineering alloys to a wider array of compositional and properties possibilities. As such, the exploration of methodologies to achieve improved microstructure and mechanical characteristics of these materials for potential applications in industry is a requirement that is experiencing extended research efforts. One example of a processing method able to expand the potential applications of these alloys is Gas Tungsten Arc Welding (GTAW), which allows to evaluate the metallurgical evolution and corresponding mechanical performance, associated to the impact of a localized heat input on the material. However, GTAW and related fusion-based welding processes are known to generate large grain sized-structures in the fusion zone, which often is detrimental to the joint performance. Thus, the integration of high temperature inoculant particles on the fusion zone during welding is a potential way to improve this region's microstructure and, therefore, its mechanical performance. In this work, we discuss the effect that the addition of TiB2 micron-sized particles have on the microstructure of a GTAW AlCoCrFeNi-based HEA. For this, the microstructure of the welds was evaluated by means of optical and electron microscopy, synchrotron X-ray diffraction and CalPhaD-based simulations. Mechanical testing was performed using microhardness mapping and tensile testing coupled with digital image correlation. The results evidenced that successful inoculation with TiB2 proved capable of altering the microstructure of the fusion zone (FZ), refining it. Nevertheless, preferential deformation in the relatively softer heat affected zone during tensile testing resulted on premature failure of the inoculated joints, due to the concomitant higher hardness of the FZ.
In-situ microstructural evolution during tensile loading of CoCrFeMnNi high entropy alloy welded joint probed by high energy synchrotron X-ray diffraction
Publication . Dias, P.; Lopes, J. G.; Curado, T.; Maawad, E.; Schell, N.; Kim, H. S.; Oliveira, J. P.; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); DCM - Departamento de Ciência dos Materiais; UNIDEMI - Unidade de Investigação e Desenvolvimento em Engenharia Mecânica e Industrial; DEMI - Departamento de Engenharia Mecânica e Industrial; Maney Publishing
The research regarding high entropy alloys (HEAs) has proved them to be suitable for engineering applications. Nevertheless, assessing their processability is key for industrial deployment. Of special relevance in terms of processing techniques arised welding. In this work, Gas Tungsten Arc Welding (GTAW) was chosen as a processing method to attest for the suitability of the equiatomic CoCrFeMnNi HEA for one of the most common real-world mechanical solicitations, tensile loading. We delve into an in-situ synchrotron X-ray diffraction analysis of the mechanical behavior of a high-performing GTAW CoCrFeMnNi HEA joint. Local analysis of the microstructure evolution, considering the base material, heat affected zone and fusion zone, was performed by tracking changes in the diffracted intensity and lattice strain. Orientation-dependent evolution is highlighted by considering partial azimuthal integration detailing texture impact across the joint. Evidence of strain concentration at specific locations is correlated with the microstructure and overall macroscopic mechanical behavior.
Evolution of microstructure and deformation mechanisms in a metastable Fe42Mn28Co10Cr15Si5 high entropy alloy
Publication . Shen, Jiajia; Zhang, Wei; Lopes, J. G.; Pei, Yutao; Zeng, Zhi; Maawad, E.; Schell, N.; Baptista, Ana C.; Mishra, Rajiv S.; Oliveira, J. P.; DEMI - Departamento de Engenharia Mecânica e Industrial; UNIDEMI - Unidade de Investigação e Desenvolvimento em Engenharia Mecânica e Industrial; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); DCM - Departamento de Ciência dos Materiais; Elsevier
In this work, a combination of in-situ high synchrotron X-ray diffraction and electron backscattered diffraction were used to systematically investigate the activation and evolution of the deformation mechanisms in an as-cast Fe42Mn28Co10Cr15Si5 metastable high entropy alloy deformed until fracture at room temperature. This work unveils the critical role of the dual-phase γ-f.c.c. / ε-h.c.p. microstructure on the deformation response of the alloy. The different deformation modes, i.e., slip, transformation induced plasticity (TRIP) and transformation induced twinning (TWIP), were seen to initiate at different loading stresses and then to overlap. Quantitative microstructural characterization, which included the evolution of the phase fraction, stress partitioning, dislocation density, c/a ratio and lattice strain for different planes, was performed to elucidate the role of each phase on the macroscopic mechanical response of the metastable high entropy alloy. Furthermore, the magnitude of the different strengthening contributions has been quantified for the first time.
Unidades organizacionais
Descrição
Palavras-chave
Contribuidores
Financiadores
Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
Número da atribuição
2020.07350.BD