Development of a TiAl turbocharger for passenger vehicles

In order to improve acceleration and to reduce the amount of harmful substances in the exhaust gases of passenger vehicles, improvement of turbocharger response is highly effective. The simplest way to do this is to apply lightweight materials for the turbine wheel, in which Ni-based superalloys are currently used. However, as the turbine wheel is exposed to exhaust gases at temperatures of 850 °C or more, normal lightweight metallic materials cannot be used. In the development work reported here, a new high-performance TiAl alloy has been developed together with the required manufacturing technology. Applicability for turbochargers has been confirmed by numerous engine tests, leading to successful practical application. High-response TiAl turbochargers are being produced by Mitsubishi Heavy Industries Ltd. using this new material, and they have been used in Mitsubishi Motors Corp. Lancer Evolution series automobiles since January 1999.