In October 1998, a new mass-produced public carinstalling titanium engine-valves (both intake and exhaust) wasreleased from TOYOTA. Both valves were manufactured via anewly developed cost-effective powder metallurgy process.Further-more, the material for the exhaust one is a uniquetitanium metal matrix composite (MMC). This material wasspecially designed in view of mechanical properties at elevatedtemperatures up to 900 deg C and productivity. The tensilestrength, high-cycle fatigue strength and creep resistance of theMMC from room temperature to 800 deg C are always superiorto those for the typical heat-resistant steel of 2l-4N. Theseproperties have been realized by the best combination of aspecial heat-resistant matrix titanium alloy and the bestreinforcement particle, TiB. The exhaust valve made of theMMC has achieved sufficient durability and reliability with amanufacturing cost acceptable for the mass-producedautomobile parts. As a result, the developed MMC practicallybecomes applicable to mass-produced public cars.
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