  [abridged] We analyze a sample of 9 massive clusters at 0.4<z<0.6 observed
with MegaCam in 4 photometric bands (g,r,i,z) from the core to a radius of 5
Mpc (~4000 galaxies). Galaxy cluster candidates are selected using photometric
redshifts computed with HyperZ. Morphologies are estimated with galSVM in two
broad morphological types (early-type and late-type). We examine the
morphological composition of the red-sequence and the blue-cloud and study the
relations between galaxies and their environment through the morphology-density
relations (T-Sigma) and the morphology-radius relation (T-R) in a mass limited
sample (log(M/Msol)>9.5). We find that the red sequence is already in place at
z~0.5 and it is mainly composed of very massive (log(M/Msol)>11.3) early-type
galaxies. These massive galaxies seem to be already formed when they enter the
cluster, probably in infalling groups, since the fraction remains constant with
the cluster radius. Their presence in the cluster center could be explained by
a segregation effect reflecting an early assembly history. Any evolution that
takes place in the galaxy cluster population occurs therefore at lower masses
(10.3<log(M/Msol)<11.3). For these galaxies, the evolution, is mainly driven by
galaxy-galaxy interactions in the outskirts as revealed by the T-Sigma
relation. Finally, the majority of less massive galaxies (9.5<log(M/Msol)<10.3)
are late-type galaxies at all locations, suggesting that they have not started
the morphological transformation yet even if this low mass bin might be
affected by incompleteness.
