双态组织高Nb-TiAl合金的缺口敏感性

Notch Sensitivity of High Nb Containing TiAl Alloy with Duplex Microstructure

摘要:

通过对圆棒状缺口试样和无缺口光滑试样进行单向拉伸试验，研究了双态组织高Nb-TiAl合金的缺口敏感性。研究表明，缺口根半径R≥0.5 mm的U型试样和缺口角度60°、R≥1 mm的V型试样的抗拉强度RmN都大于光滑试样的抗拉强度Rm，缺口敏感度NSR均大于1，合金对缺口不敏感。当缺口类型相同时，缺口敏感性随缺口根半径R的减小而增大；V型缺口敏感性大于U型缺口；对于V型缺口试样，当R=0.5 mm时，其NSR在0.98~1.03之间，RmN在Rm附近波动，易出现缺口敏感。

关键词:高Nb-TiAl合金;双态组织;缺口敏感性

Abstract:

The notch sensitivity of a high Nb containing TiAl alloy with duplex microstructure has been studied by monotonic tensile testing using round club-shaped notched and unnotched samples. The results show that the alloy doesn’t exist notch sensitivity for the specimens with U-shape notch of root radius more than 0.5 mm and those with 60° V-shape notch of root radius more than 1 mm. The strength of the notched specimens(RmN) is higher than that of the unnotched specimens(Rm) that the mean coefficient of notch sensitivity(NSR) is larger than 1. The notch sensitivity increases as the reduction of the root radius with the same notch shape. The V-shape notch is more sensitive than the U-shape, and the NSR of the V-shape notch of root radius 0.5 mm fluctuates from 0.98 to 1.03，that is RmN approximates to Rm and easier to cause notch sensitivity.

Key words:high Nb containing TiAl alloy; duplex microstructure; notch sensitivity