Abstract: A turbine engine includes a rotatable turbine having a peripheral tip and a backface. A heat shield is positioned adjacent the backface and includes an integral ring extending from a peripheral edge of the heat shield to a position spaced radially outwardly from the peripheral tip of the rotatable turbine to form a tip clearance between the ring and the peripheral tip. The turbine comprises a material having a coefficient of thermal expansion at least approximately four times greater than the coefficient of thermal expansion of the heat shield such that the turbine expands toward the ring as a result of heat within the engine, thereby reducing the tip clearance to minimize air flow along the backface and improve efficiency of the engine.