  We are interested in the energetic cost of a martensitic inclusion of volume
$V$ in austenite for the cubic-to-tetragonal phase transformation. In contrast
with the work of [Kn\"upfer, Kohn, Otto: Comm. Pure Appl. Math. 66 (2013), no.
6, 867--904], we consider domain with a corner and obtain a better scaling law
for the minimal energy ($E_{min} \sim \min(V^{2/3},V^{7/9})$). Our predictions
are in a good agreement with physical experiments where nucleation of
martensite is usually observed near the corners of the specimen.
