TY - CHAP A1 - Kutzsche, Anja A1 - Zhang, J. A1 - Appel, Fritz A1 - Leyens, Christoph A1 - Viehweger, Bernd T1 - Forging of Beta-Phase containing gamma-TiAl alloys KW - TiAl Y1 - 2006 ER - TY - CHAP A1 - Lindemann, Janny A1 - Glavatskikh, Maria A1 - Leyens, Christoph A1 - Oehring, Michael A1 - Appel, Fritz T1 - Influence of Mechanical Surface Treatments on the High Cycle Fatigue Performance of Gamma Titanium Aluminides Y1 - 2007 ER - TY - GEN A1 - Paul, Jonathan A1 - Oehring, Michael A1 - Appel, Fritz A1 - Pyczak, Florian T1 - Depth resolved near-surface residual stresses in γ-based TiAl before and after high-temperature exposure T2 - Intermetallics Y1 - 2017 SN - 0966-9795 VL - 84 SP - 103 EP - 111 ER - TY - CHAP A1 - Glavatskikh, Maria A1 - Lindemann, Janny A1 - Leyens, Christoph A1 - Oehring, Michael A1 - Appel, Fritz ED - Kim, Young-Won T1 - Surface Strengthening for Enhanced Fatigue Performance of Gamma Titanium Aluminides T2 - Structural aluminides for elevated temperatures, proceedings of the Structural Aluminides for Elevated Temperatures Symposium, held during TMS 2008 annual meeting & exhibition, New Orleans, Louisiana, USA, March 9 - 13, 2008 KW - Gamma titanium aluminides KW - Shot peening KW - Roller burnishing KW - High cycle fatigue Y1 - 2008 SN - 978-0-87339-720-9 SP - 111 EP - 118 PB - TMS CY - Warrendale, Pa. ER - TY - JOUR A1 - Lindemann, Janny A1 - Kutzsche, Anja A1 - Oehring, Michael A1 - Appel, Fritz T1 - Influence of Mechanical Surface Treatments on the Fatigue Performance of the Gamma TiAl Alloy Ti-45Al-9Nb-0.2C JF - Materials Science Forum Y1 - 2007 SN - 0255-5476 VL - 539-543 SP - 1553 EP - 1558 ER - TY - JOUR A1 - Lindemann, Janny A1 - Buque, Cesar A1 - Appel, Fritz T1 - Effect of Shot Peening on the Fatigue Performance of a Lamellar Titanium Aluminide Alloy Y1 - 2006 ER - TY - GEN A1 - Pyczak, Florian A1 - Appel, Fritz A1 - Limberg, Wolfgang A1 - Lorenz, Uwe A1 - Oehring, Michael A1 - Paul, Jonathan A1 - Schimansky, Frank-Peter T1 - Novel Processing Techniques for gamma-TiAl Alloys T2 - Materials Science Forum Y1 - 2011 SN - 1662-9752 IS - 690 SP - 145 EP - 148 ER - TY - GEN A1 - Song, Lin A1 - Appel, Fritz A1 - Pyczak, Florian A1 - Zhanbing, He A1 - Junpin, Lin A1 - Tiebang, Zhang T1 - Characterization of primary, secondary and tertiary {202¯1}<1¯014> successive internal twins in the D019 ordered hexagonal α2-Ti3Al phase T2 - Acta Materialia N2 - Due to the lack of independent slip systems and the difficulty in mechanical twinning, D019 ordered α2-Ti3Al phase is known to be of substantial mechanical anisotropy, which partly accounts for the low ductility of two-phase (α2+γ) TiAl alloys. However, recent studies have shown that in Al-rich α2 phase compression deformation twins can be activated, which could be beneficial for the ductility of the alloys. In the present study, for the first time, we have revealed a novel internal twinning mechanism of α2 phase in a TiAl alloy deformed at high temperature. Three twin generations of a common type {202¯1}[removed] were revealed: Secondary twins formed within the primary twin, and tertiary twins formed in the secondary twin. It is important to note that this internal twin structure can only be observed in the [removed] direction but not the commonly used [removed] direction. The shear plane P of all twin variants is of type {12¯10}. Due to the variation of the twinning elements between the twin variants, the twinning shear is blunted. The interfaces between the twin variants are characterized by high-resolution electron microscopy. Special attention was paid to the structure of the coherent and incoherent twin boundaries. The effect of chemical ordering is discussed. Our results also shed light on the complex twinning mechanisms in hexagonal structures. Y1 - 2022 U6 - https://doi.org/10.1016/j.actamat.2021.117391 SN - 1873-2453 IS - 222 ER - TY - GEN A1 - Song, Lin A1 - Appel, Fritz A1 - Wang, Li A1 - Oehring, Michael A1 - Hu, Xingguo A1 - Stark, Andreas A1 - He, Junyang A1 - Lorenz, Uwe A1 - Zhang, Tiebang A1 - Lin, Junpin A1 - Pyczak, Florian T1 - New insights into high-temperature deformation and phase transformation mechanisms of lamellar structures in high Nb-containing TiAl alloys T2 - Acta Materialia Y1 - 2020 U6 - https://doi.org/10.1016/j.actamat.2020.01.021 SN - 1873-2453 SN - 1359-6454 VL - 186 SP - 575 EP - 586 ER - TY - GEN A1 - Song, Lin A1 - Wang, Li A1 - Oehring, Michael A1 - Hu, Xingguo A1 - Appel, Fritz A1 - Pyczak, Florian A1 - Zhang, Tiebang T1 - Evidence for deformation twinning of the D019-α2 phase in a high Nb containing TiAl alloy T2 - Intermetallics Y1 - 2019 U6 - https://doi.org/10.1016/j.intermet.2019.03.014 SN - 0966-9795 VL - 109 SP - 91 EP - 96 ER - TY - GEN A1 - Song, Lin A1 - Appel, Fritz A1 - Liu, Wenhao A1 - Pyczak, Florian A1 - Zhang, Tiebang T1 - {11¯01} tension twins and {11¯01}-{22¯01}/{22¯01}-{11¯01} double twins in the D019 ordered hexagonal α2-Ti3Al phase T2 - Acta Materialia Y1 - 2023 U6 - https://doi.org/10.1016/j.actamat.2023.119335 VL - 260 IS - 3 ER -