Strength and toughness are at odds
with each other in coating design.
Constructing strength–toughness-integrated coatings has long
been a pursuit in materials design but is a challenge to achieve.
Conventional wisdom suggests that growth of coatings is only a uniform
cumulative growth on a two-dimensional plane. However, by constructing
growth templates and controlling the alternation of heterogeneous
materials, it subverts the traditional perception of cumulative growth
in planes and creates the fact that the coating grows on a curved
surface. Regulating the microstructure of the coating autonomously
and matching the strength and toughness of heterogeneous materials,
drawing inspiration from the multiarched structure in the nacre of
red abalone, are crucial for achieving strength–toughness integration.
Herein, we propose a new idea of coating deposition to achieve strength–toughness
integration via preconstructing a nanoscale island-like discontinuous
seed layer as a template for coating growth and then growing a nanoscale
hard/soft heterogeneous multiarched architecture in situ. We refer
to this architecture with intrinsic mechanical advantage as the “Nanoheterogeneous
Alternating Multiarched” (NHAM) architecture. We design a nacre-like
multiarched coating with a strength of 12.42 GPa and a K
IC
value of 2.12 MPa·m1/2, depositing the hard phase (TiSiCN layer) and the soft phase (Ag
layer) with the unique NHAM architecture via physical vapor deposition
technology, which exhibits a superior improvement in the strength–toughness
integration compared to that reported in other studies (increased
strength by at least 1 GPa without sacrificing toughness). The NHAM
architecture strategy provides a pathway to design strength–toughness-integrated
coatings. Two heterogeneous materials with well-matched strength and
toughness can be deposited to achieve the NHAM architecture to greatly
reflect the effect of strength–toughness integration.