Changes in lamellar microstructure by parallel twinning during creep in soft PST crystal of TiAl alloy

来源期刊：中国有色金属学报(英文版)2002年第4期

论文作者：K. Maruyama H. Y. Kim

文章页码：561 - 568

Key words：titanium aluminide; intermetallics; lamellar microstructure; creep; twinning

Abstract: Compression creep tests of a Ti-48%Al (mole fraction) alloy were carried out at 1150K with soft-orientated PST crystal. Parallel twinning took place during the creep. Changes in lamellar microstructure caused by the parallel twinning were investigated, and their effects on creep deformation behavior were discussed. The results show that the parallel twinning occurs in an early stage of creep, and makes significant contribution to creep strain in the domains favorably oriented for the twinning. The nucleation of parallel twins finishes at a strain of about 3%. There is a critical resolved shear stress for parallel twinning, and it is about 50MPa in the Ti-48%Al PST crystals at 1150K. The activity of parallel twinning increases with increasing applied stress or in a coarse lamellar material. The addition of parallel twins reduces the average value of lamellar spacing. In general, the refinement of lamellar structure should improve creep resistance. However the strengthening by parallel twinning is not evident in creep of the soft PST crystals because the soft deformation modes are the dominant deformation mode in the crystals.