Chemical short-range order and tension–compression asymmetry in MoNbTaWZrxTi1-x refractory high-entropy alloys

Reis H. A., Sezer R., Öztürk B.

INTERNATIONAL JOURNAL OF REFRACTORY METALS AND HARD MATERIALS, cilt.142, ss.108129-108139, 2027 (SCI-Expanded, Scopus)

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 142
  • Basım Tarihi: 2027
  • Doi Numarası: 10.1016/j.ijrmhm.2026.108129
  • Dergi Adı: INTERNATIONAL JOURNAL OF REFRACTORY METALS AND HARD MATERIALS
  • Derginin Tarandığı İndeksler: Academic Search Ultimate (EBSCO), Engineering Source (EBSCO), Scopus, Science Citation Index Expanded (SCI-EXPANDED), Chemical Abstracts Core, Chimica, Compendex, INSPEC
  • Sayfa Sayıları: ss.108129-108139
  • Karadeniz Teknik Üniversitesi Adresli: Evet

Özet

Chemical short-range order (SRO) affects the deformation response of refractory high-entropy alloys (RHEAs), with the extent of this effect depending on alloy composition and loading mode. Here, hybrid Monte Carlo/molecular dynamics (MC/MD) simulations were performed to investigate temperature-dependent chemical ordering of MoNbTaWZrxTi1-x RHEAs from 300 to 1200 K. Pair-resolved Warren–Cowley analysis revealed shell-dependent atomic-pair correlations, with 600 K exhibiting the strongest SRO among the sampled temperatures under the present finite MC/MD protocol. Notably, Mo-Nb, W-Ta, and Nb-Ti exhibited the strongest first-shell ordering pairs, whereas Nb-Ta, W-Mo, and Ti-Ti showed pronounced avoidance. To relate ordering with mechanical response, tensile and compressive simulations were conducted at 300 K for random and SRO configurations. Under the present ADP model and single-crystal loading conditions, progressive Ti-to-Zr substitution reduced the elastic modulus and peak stress by 19–24%, depending on the loading mode and ordering state. Within this framework, SRO partly mitigated this softening, with predicted peak-stress increases of 15–23% in tension and 10–14% in compression. Tensile post-peak deformation involved extended 1/2⟨111⟩ dislocation networks associated with {112}-oriented traces, with most segments exhibiting screw character. In contrast, compression produced sparse dislocations and was primarily accommodated by {112}-oriented planar faults and twinning-related atomic rearrangements. The SRO configuration exhibited a less connected tensile defect network and more localized compression-induced planar faults than the random configuration, without changing prevailing defect families. Overall, the results show that mechanical resistance and defect morphology depend on composition, chemical state, and loading mode.

Chemical short-range order (SRO) affects the deformation response of refractory high-entropy alloys (RHEAs), with the extent of this effect depending on alloy composition and loading mode. Here, hybrid Monte Carlo/molecular dynamics (MC/MD) simulations were performed to investigate temperature-dependent chemical ordering of MoNbTaWZrxTi1-x RHEAs from 300 to 1200 K. Pair-resolved Warren–Cowley analysis revealed shell-dependent atomic-pair correlations, with 600 K exhibiting the strongest SRO among the sampled temperatures under the present finite MC/MD protocol. Notably, Mo-Nb, W-Ta, and Nb-Ti exhibited the strongest first-shell ordering pairs, whereas Nb-Ta, W-Mo, and Ti-Ti showed pronounced avoidance. To relate ordering with mechanical response, tensile and compressive simulations were conducted at 300 K for random and SRO configurations. Under the present ADP model and single-crystal loading conditions, progressive Ti-to-Zr substitution reduced the elastic modulus and peak stress by 19–24%, depending on the loading mode and ordering state. Within this framework, SRO partly mitigated this softening, with predicted peak-stress increases of 15–23% in tension and 10–14% in compression. Tensile post-peak deformation involved extended 1/2⟨111⟩ dislocation networks associated with {112}-oriented traces, with most segments exhibiting screw character. In contrast, compression produced sparse dislocations and was primarily accommodated by {112}-oriented planar faults and twinning-related atomic rearrangements. The SRO configuration exhibited a less connected tensile defect network and more localized compression-induced planar faults than the random configuration, without changing prevailing defect families. Overall, the results show that mechanical resistance and defect morphology depend on composition, chemical state, and loading mode.