and matrix were tested on an HXD-1000TMC Vickers tester with a
load of 25 gf.
The indentation method has been generally used to measure
the fracture toughness of brittle materials, such as ceramics and
glass [35]. Hence, fracture toughness of borides (intermetallics
with intrinsic brittleness), can be measured perfectly by the IM
method [29–33]. By measuring the length of cracks induced with
the Vickers indenter, the fracture toughness can be readily
obtained using the equation as follows