Publication detail

Effects of annealing temperature on microstructure and mechanical properties of cold sprayed AA7075

JUDAS, J. ZAPLETAL, J. ŘEHOŘEK, L. JAN, V.

English title

Effects of annealing temperature on microstructure and mechanical properties of cold sprayed AA7075

Type

conference paper

Language

en

Original abstract

This paper examines the softening behaviour of cold sprayed 7075 aluminum alloy after isothermal annealing. The as-received powder was deposited by a high-pressure cold spray device using heated nitrogen as propellant gas. To investigate the effects of post-deposition heat treatment, the excised samples were isochronally annealed in the temperature range of 200 to 400 °C. The feedstock powder and the free-standing coatings were initially characterized through various electron microscopy techniques (SEM, EDS, EBSD) and relevant microstructural features were determined. Mechanical properties of the as-sprayed and heat-treated samples were evaluated by quasi-static tensile and microhardness testing. It has been shown that extensive plastic deformation during cold spraying resulted in a dense coating with relatively low internal porosity. Specimens in an as-deposited state possessed a high level of strain hardening and exhibited a brittle rupture associated with intersplat cracking. When subjected to heat treatment, the cold spray deposits showed a general trend of microhardness reduction and progressive sintering of the microstructure with increasing annealing temperature. Furthermore, post-mortem observation revealed a gradual transition in fracture mechanism, manifested by improving material ductility and the occurrence of typical dimple morphology. The aspects responsible for the softening of the cold sprayed 7075 alloys are discussed further.

English abstract

This paper examines the softening behaviour of cold sprayed 7075 aluminum alloy after isothermal annealing. The as-received powder was deposited by a high-pressure cold spray device using heated nitrogen as propellant gas. To investigate the effects of post-deposition heat treatment, the excised samples were isochronally annealed in the temperature range of 200 to 400 °C. The feedstock powder and the free-standing coatings were initially characterized through various electron microscopy techniques (SEM, EDS, EBSD) and relevant microstructural features were determined. Mechanical properties of the as-sprayed and heat-treated samples were evaluated by quasi-static tensile and microhardness testing. It has been shown that extensive plastic deformation during cold spraying resulted in a dense coating with relatively low internal porosity. Specimens in an as-deposited state possessed a high level of strain hardening and exhibited a brittle rupture associated with intersplat cracking. When subjected to heat treatment, the cold spray deposits showed a general trend of microhardness reduction and progressive sintering of the microstructure with increasing annealing temperature. Furthermore, post-mortem observation revealed a gradual transition in fracture mechanism, manifested by improving material ductility and the occurrence of typical dimple morphology. The aspects responsible for the softening of the cold sprayed 7075 alloys are discussed further.

Keywords in English

Cold Spray; 7075 aluminum alloy; isothermal annealing; tensile testing; electron microscopy

Released

01.01.2023

Publisher

Elsevier

ISSN

2452-3216

Book

10th International Conference on Materials Structure and Micromechanics of Fracture

Volume

43

Number

1

Pages from–to

160–165

Pages count

6

BIBTEX


@inproceedings{BUT183216,
  author="Jakub {Judas} and Josef {Zapletal} and Lukáš {Řehořek} and Vít {Jan},
  title="Effects of annealing temperature on microstructure and mechanical properties of cold sprayed AA7075",
  booktitle="10th International Conference on Materials Structure and Micromechanics of Fracture",
  year="2023",
  volume="43",
  number="1",
  month="January",
  pages="160--165",
  publisher="Elsevier",
  issn="2452-3216"
}