A static mixer for the through-mixing of a flow in a line conducting the flow, more preferably of an exhaust system of a combustion engine with several guide vanes. To create adequate through-mixing at low flow velocity and a through-flow resistance that is not too high at high flow velocity, the guide vanes are produced of a shape memory alloy wherein below a predetermined limit temperature the guide vanes have at least one low-temperature shape and above the limit temperature the guide vanes have at least one high-temperature shape, which differs from the low-temperature shape through a reduced through-flow resistance of the mixer.