“…The calculated value of “υ” for Hf 2 AX (A═Al, Si and X═C, N) MAX phases is less than its threshold, which indicates the brittle character of Hf 2 AX MAX phases. For hexagonal Hf 2 AX compounds, the expressions
and
refer to the Cauchy pressure (
),
49–52 which is used to predict the brittleness or ductility of the studied compounds. If
and
, the solid is ductile; otherwise, it is brittle.…”