The influences of environment in solute heat treatment and aging and pre-aging at room temperature on the age hardening behavior of Ti-14 and 20 mass% Mo alloys at 623 K were studied by Vickers hardness measurements. The solution heat treatments were performed in vacuums of 1.3 mPa and 8 Pa. The atmosphere, a pure argon current and a vacuum were the environments. The periods of pre-aging were 1.6 × 105 s for the short pre-aging and 1.0 × 106-3.7 × 107 s for the long one. The specimens which were solution heat treated in each vacuum and pre-aged for 1.6 × 105 s showed two-stage hardening. The first stage seemed to be due to a product formed by the reaction of quenched-in vacancies, interstitial atoms and metallic atoms. The second stage was due to the formation of an aged omega phase. The age hardening behavior of the specimen pre-aged for a short period was more active than that of the specimen pre-aged for a long period in spite of solution heat treatment in either vacuum. The role of quenched-in vacancies was important in Ti-20 mass% Mo alloys in connection with pre-aging at room temperature. The higher the oxygen content in the environments during aging, the greater the hardness of the surface layer and interior of Ti-14 mass% Mo alloys.
|Number of pages||5|
|Publication status||Published - Feb 1989|
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