  The ability of high-entropy alloys (HEAs) for hydrogen storage is a rather
new topic in the hydrogen community. HEAs with the C14 Laves phase have shown a
high potential to reversibly store hydrogen at room temperature, but most of
these alloys require a high-temperature activation treatment. This study
explores the role of interphase boundaries on the easy activation of HEAs at
room temperature. Two chemically similar HEAs with single and dual phases,
TiV1.5ZrCr0.5MnFeNi (C14 + 4 vol% BCC phases) and TiV1.5Zr1.5CrMnFeNi (single
C14 phase), are designed and synthesized. While the dual-phase alloy readily
absorbs hydrogen at room temperature without any activation treatment, the
single-phase alloy requires a high-temperature activation. It is suggested that
interphase boundaries not only provide pathways for easy hydrogen transport and
activation of HEAs at room temperature but also act as active sites for
heterogeneous nucleation of hydride. This study introduces interphase-boundary
generation as an effective strategy to address the activation drawback of HEAs.
