Evaluation of Ti-48Al-2Cr-2Nb Under Fretting Conditions

摘要

The fretting behavior of Ti-48Al-2Cr-2Nb~2 (γ-TiAl) in contact with a typical nickel-base superalloy was examined in air at temperatures from 296 to 823 K (23 to 550 °C). The interfacial adhesive bonds between Ti-48Al-2Cr-2Nb and superalloy were generally stronger than the cohesive bonds within Ti-48Al-2Cr-2Nb. The failed Ti-48Al-2Cr-2Nb debris subsequently transferred to the superalloy. In reference experiments conducted with Ti-6A1-4V against superalloy under identical fretting conditions, the degree of transfer was greater for Ti-6Al-4V than for Ti-48Al-2Cr-2Nb. Wear of Ti-48Al-2Cr-2Nb generally decreased with increasing fretting frequency. The increasing rate of oxidation at elevated temperatures led to a drop in wear at 473 K. However, fretting wear increased as the temperature was increased from 473 to 823 K. At 723 and 823 K, oxide film disruption generated cracks, loose wear debris, and pits on the Ti-48Al-2Cr-2Nb wear surface. Both increasing slip amplitude and increasing load tended to produce more metallic wear debris, causing severe abrasive wear in the contacting metals.