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<p>The interplay between configurational entropy and the enthalpy of ordered structures governs phase stability in compositionally complex alloys. In the refractory alloy Re<sub>0.6</sub>(NbTiZrHf)<sub>0.4</sub>, this balance is particularly delicate: pressure stabilizes a disordered body-centred-cubic (bcc) solid solution over the ambient hexagonal Laves phase via a martensitic route. Using in situ laser heating with synchrotron X-ray diffraction in a diamond-anvil cell, we demonstrate that the metastable bcc phase can be controllably transformed into a large-scale 2 × 2 × 2 B2-type superstructure with primitive-cubic symmetry (<InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(\:Pm\stackrel{-}{3}m\)</EquationSource> </InlineEquation>). This long-period ordered phase is crystallographically distinct from conventional B2 ordering in multicomponent alloys, establishing a pathway to achieve chemical ordering from pressure-stabilized solid solutions. More broadly, these findings demonstrate that combining compression with subsequent thermal activation can unlock recoverable three-dimensional superstructures, offering new opportunities to tailor strength, transport properties, and stability in compositionally complex alloys.</p>

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Pressure–temperature route from disordered BCC to a 2 × 2 × 2 B2 superstructure

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年12月24日

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  • Raimundas Sereika,
  • Andrew D. Pope,
  • Caleb M. Knight,
  • Kallol Chakrabarty,
  • Yogesh K. Vohra

摘要

The interplay between configurational entropy and the enthalpy of ordered structures governs phase stability in compositionally complex alloys. In the refractory alloy Re0.6(NbTiZrHf)0.4, this balance is particularly delicate: pressure stabilizes a disordered body-centred-cubic (bcc) solid solution over the ambient hexagonal Laves phase via a martensitic route. Using in situ laser heating with synchrotron X-ray diffraction in a diamond-anvil cell, we demonstrate that the metastable bcc phase can be controllably transformed into a large-scale 2 × 2 × 2 B2-type superstructure with primitive-cubic symmetry ( \(\:Pm\stackrel{-}{3}m\) ). This long-period ordered phase is crystallographically distinct from conventional B2 ordering in multicomponent alloys, establishing a pathway to achieve chemical ordering from pressure-stabilized solid solutions. More broadly, these findings demonstrate that combining compression with subsequent thermal activation can unlock recoverable three-dimensional superstructures, offering new opportunities to tailor strength, transport properties, and stability in compositionally complex alloys.