Microstructure, mechanical properties and fracture mechanisms in a 7017 aluminium alloy tailored for powder bed fusion – laser beam
Journal article, 2023

This study addressed a 7017 Al-alloy tailored for powder bed fusion – laser beam (PBF-LB) process. The alloy was prepared by mixing 3 wt% Zr and 0.5 wt% TiC powder to standard pre-alloyed 7017 grade aluminium powder. This made printing of the alloys possible avoiding solidification cracking in the bulk and achieving high relative density (99.8 %). Such advanced alloys have significantly higher Young's modulus (>80 GPa) than conventional Al-alloys (70–75 GPa), thus making them attractive for applications requiring high stiffness. The resulting microstructure in as-printed condition was rich in particles originating from admixed powders and primary precipitates/inclusions originating from the PBF-LB process. After performing a T6-like heat treatment designed for the PBF-LB process, the microstructure changed: Zr-nanoparticles and Fe- or Mg/Zn- containing precipitates formed thus providing 75 % increase in yield strength (from 254 MPa to 444 MPa) at the cost of decreasing ductility (∼20 % to ∼9 %). In-situ tensile testing combined with SXCT, and ex-situ tensile testing combined with fracture analysis confirmed that the fracture initiation in both conditions is highly dependent on defects originated during printing. However, cracks are deflected from decohesion around Zr-containing inclusions/precipitates embedded in the Al-matrix. This deflection is seen to improve the ductility of the material.

Powder bed fusion – Laser beam

Strengthening mechanisms

Zirconium

Crack propagation

X-ray computed tomography

Additive manufacturing

Author

Bharat Mehta

Chalmers, Industrial and Materials Science, Materials and manufacture

T. Mishurova

Federal Institute for Materials Research and Testing

S. Evsevleev

Federal Institute for Materials Research and Testing

Henning Markötter

Federal Institute for Materials Research and Testing

G. Bruno

Federal Institute for Materials Research and Testing

Eduard Hryha

Chalmers, Industrial and Materials Science, Materials and manufacture

Lars Nyborg

Chalmers, Industrial and Materials Science, Materials and manufacture

Eero Virtanen

EOS Electro Optical Systems Finland Oy

Materials and Design

0264-1275 (ISSN) 1873-4197 (eISSN)

Vol. 226 111602

Subject Categories

Manufacturing, Surface and Joining Technology

Other Materials Engineering

Metallurgy and Metallic Materials

DOI

10.1016/j.matdes.2023.111602

More information

Latest update

1/27/2023