Unusual two-step dealloying mechanism of nanoporous TiVNbMoTa high-entropy alloy during liquid metal dealloying

Soo Joo, I. V. Okulov, H. Kato

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)


In this study, 3D interconnected nanoporous (3DNP) TiVNbMoTa HEAs were synthesized from the (TiVNbMoTa)25Ni75 as-cast precursor alloy using the liquid metal dealloying (LMD). The as-cast precursor demonstrated the initial dendritic microstructure consisting of fcc and hcp phases. At 600 °C after 1 h, tiny ligaments about 10 nm thickness were homogeneously synthesized. At 900 °C, the bulk transformation intensively took place at the original precursor alloy. Specifically, the dendritic morphology of the original phases disappeared, and the fraction of fcc phase decreased from 63% to 20%. This pre-transformation behavior significantly influences the dealloying mechanism. Kurdjumov–Sachs orientation relationship (OR) governed the ligament formation at the prior fcc phase while Pitsch-Schrader (P–S) OR controlled the ligament evolution at the prior hcp phase. An unusual mechanism of two-step dealloying was observed at the fcc phase region when the dealloying rate was decreased at the reaction front. The dissolution of Ni occurs by stepwise transformations of fcc=>hcp=>bcc. The prior fcc grain was transformed to the abnormally large hcp ligaments and tiny bcc ligaments. Then, the abnormal hcp ligaments were further dealloyed to smaller bcc ligaments following the P–S OR. This study pave the way for the design of compositionally complex porous materials with a customized morphology and advanced physical properties by dealloying.

Original languageEnglish
Pages (from-to)2945-2953
Number of pages9
JournalJournal of Materials Research and Technology
Publication statusPublished - 2021 Sept 1


  • Abnormal transformation
  • Dealloying mechanism
  • High-entropy alloy
  • Liquid metal dealloying
  • Nanoporous

ASJC Scopus subject areas

  • Ceramics and Composites
  • Biomaterials
  • Surfaces, Coatings and Films
  • Metals and Alloys


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