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

Materials & Design

Katharina Käsznar¹  Matthias Markl²  Jozef Keckes²  Svea Mayer²  Christoph Breuning³  David Wimler³  Helmut Clemens³  Carolin Körner³  Michael Musi³ 

[1] Corresponding author.;Chair of Materials Science and Engineering for Metals, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany;Department of Materials Science, Montanuniversität Leoben, Leoben, Austria;

关键词: Additive manufacturing;    Titanium aluminides;    Microstructure;    Crystal orientation;    Heat treatment;   

DOI  :  

来源: DOAJ

【 摘 要 】

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.

【 授权许可】

Unknown