There is no IMC composition can be identified in phase diagram of In/Sn. There are some compositions such as In3Sn or InSn4 cited in earlier literature. Those composition should be regarded as approximate representation of solid solution of In/Sn.
If there is any IMC of In/Sn to be reported in the future, which I doubt, the material property certainly will not be brittle and hard. In the manufacturing of In/Sn alloy systems, no brittle textures have been experienced or reported.