Cast irons are provided which have no intentional addition of molybdenum (Mo) and which have compositions with additional silicon that provide certain advantages, such as lower cost, higher use temperatures, and increased tensile strength, over conventional Mo-bearing cast irons. In the cast irons, Mo is absent or present only as an impurity element.
CONTRACTUAL ORIGIN OF THE INVENTION
 This invention was made with Government support under Agreement No. ERD-96-XJ190 awarded by the Department of Energy. The Government may have certain rights in the invention.