TY - JOUR

T1 - Advancement of Compositional and Microstructural Design of Intermetallic γ-TiAl Based Alloys Determined by Atom Probe Tomography

AU - Klein, Thomas

AU - Clemens, Helmut

AU - Mayer, Svea

PY - 2016/9/6

Y1 - 2016/9/6

N2 - Advanced intermetallic alloys based on the γ-TiAl phase have become widely regarded as most promising candidates to replace heavier Ni-base superalloys as materials for high-temperature structural components, due to their facilitating properties of high creep and oxidation resistance in combination with a low density. Particularly, recently developed alloying concepts based on a β-solidification pathway, such as the so-called TNM alloy, which are already incorporated in aircraft engines, have emerged offering the advantage of being processible using near-conventional methods and the option to attain balanced mechanical properties via subsequent heat-treatment. Development trends for the improvement of alloying concepts, especially dealing with issues regarding alloying element distribution, nano-scale phase characterization, phase stability, and phase formation mechanisms demand the utilization of high-resolution techniques, mainly due to the multi-phase nature of advanced TiAl alloys. Atom probe tomography (APT) offers unique possibilities of characterizing chemical compositions with a high spatial resolution and has, therefore, been widely used in recent years with the aim of understanding the materials constitution and appearing basic phenomena on the atomic scale and applying these findings to alloy development. This review, thus, aims at summarizing scientific works regarding the application of atom probe tomography towards the understanding and further development of intermetallic TiAl alloys.

AB - Advanced intermetallic alloys based on the γ-TiAl phase have become widely regarded as most promising candidates to replace heavier Ni-base superalloys as materials for high-temperature structural components, due to their facilitating properties of high creep and oxidation resistance in combination with a low density. Particularly, recently developed alloying concepts based on a β-solidification pathway, such as the so-called TNM alloy, which are already incorporated in aircraft engines, have emerged offering the advantage of being processible using near-conventional methods and the option to attain balanced mechanical properties via subsequent heat-treatment. Development trends for the improvement of alloying concepts, especially dealing with issues regarding alloying element distribution, nano-scale phase characterization, phase stability, and phase formation mechanisms demand the utilization of high-resolution techniques, mainly due to the multi-phase nature of advanced TiAl alloys. Atom probe tomography (APT) offers unique possibilities of characterizing chemical compositions with a high spatial resolution and has, therefore, been widely used in recent years with the aim of understanding the materials constitution and appearing basic phenomena on the atomic scale and applying these findings to alloy development. This review, thus, aims at summarizing scientific works regarding the application of atom probe tomography towards the understanding and further development of intermetallic TiAl alloys.

KW - titanium aluminides based on -TiAl

KW - atom probe tomography

KW - alloy design

KW - microstructure formation

KW - interfacial segregation

KW - hardening effects

KW - phase stability

KW - site-specific specimen preparation

U2 - 10.3390/ma9090755

DO - 10.3390/ma9090755

M3 - Article

VL - 9.2016

SP - 755

EP - 774

JO - Materials

JF - Materials

SN - 1996-1944

IS - 9

M1 - 755

ER -