A movable wall member in the form of an exhaust valve spindle (1) or a piston (7) in an internal combustion engine is on the side of the wall member facing a combustion chamber provided with a hot-corrosion-resistant material (5, 14) made from a particulate starting material of an alloy containing nickel and chromium which by a HIP process has been unified to a coherent material substantially without melting the starting material. The corrosion-resistant material has a hardness of less than 310 HV measured at approximately 20 DEG C after the material has been heated to a temperature within the range of 550-850 DEG C for more than 400 hours.