Cast iron alloys have application limits with regard to temperature. By means of the use of cobalt an optimal ferritic structure can be achieved such that with an alloy containing silicon 2.0-4.5 wt. %, cobalt 0.5-5 wt. %, carbon 2.5-4 wt. %, molybdenum≦1 wt. %, manganese≦0.25 wt. %, nickel≦0.3 wt. %, the remainder iron where the proportion of silicon cobalt and molybdenum is less than 7.5 wt. % the application limits are shifted to higher temperatures.