TY - JOUR

T1 - How electron beam melting tailors the Al-sensitive microstructure and mechanical response of a novel process-adapted y-TiAl based alloy

AU - Wimler, David

AU - Käsznar, Katharina

AU - Musi, Michael

AU - Breuning, Christoph

AU - Markl, Matthias

AU - Keckes, Jozef

AU - Clemens, Helmut

AU - Körner, Carolin

AU - Mayer, Svea

N1 - Publisher Copyright: © 2021 The Authors

PY - 2021/12/15

Y1 - 2021/12/15

N2 - Additive manufacturing of lightweight intermetallic γ-TiAl based alloys combines process-related freedom of design with material-specific excellent high-temperature properties. Nevertheless, where locally melting the powder by an electron beam, there is a risk that Al evaporates due to its high vapor pressure, causing compositional and microstructural variations. This work investigates the impact of different process parameters on the total and local Al-content as well as the resulting as-built and heat-treated microstructure in a complex multiphase Ti-44.8Al-4.1Nb-0.7W-1.1Zr-0.4Si-0.5C-0.1B (at.%) alloy. The examinations applied are complementary, employing electron microscopy, X-ray spectroscopy and diffraction experiments with synchrotron X-ray radiation, supported by numerical simulations. The mechanical anisotropy of the heat-treated microstructure was analyzed by micro-hardness measurements. The results demonstrate that the amount of γ-TiAl phase decreases with increasing energy input of the electron beam in the as-built and heat-treated microstructure owing to the total and local loss of Al. Besides, the investigations of the crystal orientations within the multiphase alloy reveal a preferred orientation of the γ phase at high energy inputs. This follows from the fact that the preferred γ orientation is inherited through directional solidification of the β phase. The obtained process-microstructure-property relationships show that tailor-made material properties of additively manufactured γ-TiAl components are achievable.

AB - Additive manufacturing of lightweight intermetallic γ-TiAl based alloys combines process-related freedom of design with material-specific excellent high-temperature properties. Nevertheless, where locally melting the powder by an electron beam, there is a risk that Al evaporates due to its high vapor pressure, causing compositional and microstructural variations. This work investigates the impact of different process parameters on the total and local Al-content as well as the resulting as-built and heat-treated microstructure in a complex multiphase Ti-44.8Al-4.1Nb-0.7W-1.1Zr-0.4Si-0.5C-0.1B (at.%) alloy. The examinations applied are complementary, employing electron microscopy, X-ray spectroscopy and diffraction experiments with synchrotron X-ray radiation, supported by numerical simulations. The mechanical anisotropy of the heat-treated microstructure was analyzed by micro-hardness measurements. The results demonstrate that the amount of γ-TiAl phase decreases with increasing energy input of the electron beam in the as-built and heat-treated microstructure owing to the total and local loss of Al. Besides, the investigations of the crystal orientations within the multiphase alloy reveal a preferred orientation of the γ phase at high energy inputs. This follows from the fact that the preferred γ orientation is inherited through directional solidification of the β phase. The obtained process-microstructure-property relationships show that tailor-made material properties of additively manufactured γ-TiAl components are achievable.

UR - http://www.scopus.com/inward/record.url?scp=85118500547&partnerID=8YFLogxK

U2 - 10.1016/j.matdes.2021.110187

DO - 10.1016/j.matdes.2021.110187

M3 - Article

VL - 212.2021

JO - Materials and Design

JF - Materials and Design

SN - 0264-1275

IS - 15 December

M1 - 110187

ER -