Atomic scale characterization of a pure Al – galvanized steel spot magnetic pulse joint interface

• Published in: Materials characterization Vol. 153; pp. 251 - 260
• Main Authors: Avettand-Fènoël, M.-N., Marinova, M., Taillard, R.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.07.2019; Elsevier
• Series: Materials Characterization
• Subjects: Aluminum - galvanized steel spot magnetic pulse welding; Chemical Sciences; Condensed Matter; HAADF; HR(S)TEM; Interface; Material chemistry; Materials Science; Microstructure; Physics; STEM-EDX; STEM-EDX; Aluminum - galvanized steel spot magnetic pulse welding; HR(S)TEM; Microstructure; Interface; HAADF; Aluminum - galvanized steel spot magnetic; pulse welding
• ISSN: 1044-5803; 1873-4189
• DOI: 10.1016/j.matchar.2019.05.016

The bonding interface of pure Al – galvanized steel spot magnetic pulse welds was characterized at the atomic scale. The Al-Zn interface microstructure is worthy of attention as it contains a few micrometers thick biphased layer. This singular layer consists of an aggregate of grains with a 200 to 400 nm size containing islands of either Al or Zn solid solutions oversaturated in Zn or Al, respectively. Inside a grain, some mottled contrasts with a size in-between 5 and 10 nm correspond to fluctuant solute contents. Besides, some native oxides have been dissolved at the interface suggesting the incorporation of oxygen atoms in the biphased layer. Large and elongated (Al,Fe,Si) particles primitively contained in the base Al were also dissolved which gives rise to some round shaped Si particles in the biphased layer. All these microstructural features and changes are consistent with a ballistic origin. Due to both the absence of solidification defects and the rather planar morphology of the bonding interface, the process is expected to occur at the solid state. •The dissimilar magnetic pulse joint interface is formed via a ballistic mechanism.•The large (Al + Zn) bonding interface is expected to form at the solid state.•The randomly distributed grains at the interface present various crystal orientations.•Oversaturated Al and Zn based solid solutions with local enrichments are detected.•Precipitates dissolution and formation occurred during welding at the interface.