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Abnormal acceleration of creep deformation rate above 700 degree C in the orthorhombic based Ti-22Al-27Nb alloy
For the past decade, Ti2AlNb-based alloys have been investigated for being applied to the structural materials in aerospace engine. In this study, creep tests of Ti-22Al-27Nb (at.%) alloys are conducted at a constant tensile stress of 200MPa at the various temperatures in the range from 650 to 750 degree C. It is observed that the creep deformation rate of the O+bcc dual phase alloys is abnormally increased at temperatures above 700 degree C. The results of TEM investigation show that the active slip systems are varied and the density of dislocation is increased with increasing temperature above 700 degree C. In this temperature range, prismatic dislocations in the orthorhombic phase are newly generated from O-bcc interfaces by the result of phase transformation and the movement of the prismatic dislocations is very active compared to the basal slip system. Therefore, it is suggested that the phase transformation of bcc to O phase activates another slip system by the abundant supply of actively moving dislocations, thereby accelerating creep deformation rate at the elevated temperature above 700 degree C.
Abnormal acceleration of creep deformation rate above 700 degree C in the orthorhombic based Ti-22Al-27Nb alloy
For the past decade, Ti2AlNb-based alloys have been investigated for being applied to the structural materials in aerospace engine. In this study, creep tests of Ti-22Al-27Nb (at.%) alloys are conducted at a constant tensile stress of 200MPa at the various temperatures in the range from 650 to 750 degree C. It is observed that the creep deformation rate of the O+bcc dual phase alloys is abnormally increased at temperatures above 700 degree C. The results of TEM investigation show that the active slip systems are varied and the density of dislocation is increased with increasing temperature above 700 degree C. In this temperature range, prismatic dislocations in the orthorhombic phase are newly generated from O-bcc interfaces by the result of phase transformation and the movement of the prismatic dislocations is very active compared to the basal slip system. Therefore, it is suggested that the phase transformation of bcc to O phase activates another slip system by the abundant supply of actively moving dislocations, thereby accelerating creep deformation rate at the elevated temperature above 700 degree C.
Abnormal acceleration of creep deformation rate above 700 degree C in the orthorhombic based Ti-22Al-27Nb alloy
Yang, Seung-Jin (author) / Nam, Soo-Woo (author) / Hagiwara, Masuo (author)
Journal of Alloys and Compounds ; 368 ; 197-210
2004
14 Seiten, 25 Quellen
Article (Journal)
English
Aluminiumlegierung , Nioblegierung , Kriechen (Werkstoff) , Zugspannung , Kriechversuch , Phasenumwandlung , Wärmebehandlung , intermetallische Verbindung , Pulvermetallurgie , Hochtemperaturverhalten , Transmissionselektronenmikroskopie , hochwarmfeste Legierung , Titanaluminiumnioblegierung , Kriechverformung , beschleunigtes Kriechen , orthorhombische Struktur , Hochtemperatureffekt
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