A proof of concept: Thermodynamics of aluminum - transition metal highly concentrated alloys

Autor(es)

Schon, Claudio Geraldo ^{[1, 2]} ; Duong, Thien ^[1] ; Wang, Yuhao ^[1] ; Arroyave, Raymundo ^{[1, 3, 4]}

Afiliação do(s) autor(es)

^[1] Texas A&M Univ, Dept Mat Sci & Engn, 575 Ross St, College Stn, TX 77843 - USA

^[2] Univ Sao Paulo, Escola Politecn, Dept Met & Mat Engn, Av Prof Mello Moraes 2463, BR-05508900 Sao Paulo, SP - Brazil

^[3] Texas A&M Univ, Dept Ind & Syst Engn, 575 Ross St, College Stn, TX 77843 - USA

^[4] Texas A&M Univ, Dept Mech Engn, 575 Ross St, College Stn, TX 77843 - USA

• Tipo de documento: Artigo Científico
• Fonte: Journal of Alloys and Compounds; v. 781, p. 595-605, APR 15 2019.
• Citações Web of Science: 2

Resumo

In a previous work by the present authors (Acta Mater. 148, 2018, 263-279), the thermodynamics of V - Nb-Ta-Mo-W highly concentrated alloy at equiatomic concentration was investigated using the cluster variation method in the irregular tetrahedron approximation. It was shown that the disordered solid solution is stabilized in this highly concentrated area of the system as prescribed by the high entropy alloy (HEA) paradigm. The configurational entropy, however, has only a minor (and sometimes contrary) influence in this stabilization. It was then postulated that configurational frustration, i.e. the competition between conflicting interactions, is the more relevant factor in the stabilization of the highly-concentrated alloys. The present work elaborates this idea by further considering the cases of V-Nb-Mo-Al and V-Nb-W - Al quaternary systemas and the corresponding quinary systems with Ta addition. The quaternary system are characterized by strong Al - M pair interactions that could enhance configurational frustration. The introduction of Ta, with weaker Ta - Al and practically non-existing Ta - Nb interactions, is meant to disrupt the frustration, hence leading to a decrease of the stability of the disordered alloys. It was shown that V-Nb-Mo-Al and its quinary do not exhibit configurational frustration as expected, since a stable compound with stoichiometry VMoNbAl is formed, and the stability of their disordered alloys (A2) is low. On the contrary, V-Nb-W-Al and its quinary demonstrated strong configurational frustration and correspondingly a stronger A2 stabilization. Deviations from equiatomic composition were also investigated and even stronger A2 stabilization was observed in this case. These results show that the stabilization of the disordered phase can only be attributed to configurational frustration, corroborating the previous work's conclusion that the effect of configurational entropy is only marginal in this stabilization. (C) 2018 Elsevier B.V. All rights reserved. (AU)

• Processo FAPESP: 16/25248-3 - Resolvendo a questão da escala de temperaturas em cálculos de diagramas de fases por primeiros princípios
• Beneficiário: Claudio Geraldo Schon
• Modalidade de apoio: Bolsas no Exterior - Pesquisa