We use infrared thermography to monitor the cooling kinetics of a millifluidic diphasic flow comprising a fusible alloy and silicone oil ; the flow is generated at high temperature and then reaches a cooler environment. Above the solidification point of the alloy, the flow pattern is analogous to that of immiscible fluids with a transition from drops to jets depending on the flow conditions. Below the solidification temperature of the alloy, the flow may become unstable and clog depending on the amount of metal drops present in the diphasic flow. At low concentration of drops in the flow, the production of solidified monodisperse particles becomes continuous and we identify some parameters that permit us to tune their geometry, either spheres, ellipsoids, or rods.