Materials for Extreme Environments

Overview

In materials designed for extreme environments, such as high temperatures and corrosive conditions, intermetallic particles play a critical role in both corrosion behavior and high-temperature deformation. In alloys like Al-Si-Cu-Ni and Al-Si-Mg-Cu-Mn, intermetallics act as cathodic sites that can accelerate pitting corrosion, particularly under chloride exposure, by altering local electrochemical potentials. On the other hand, these particles influence high-temperature tensile properties by interacting with dislocations. While they can enhance strength through dislocation pinning, they may also lead to thermal instability or localized failure. The balance between mechanical strength and corrosion resistance is thus dependent on the distribution and behavior of intermetallics, making them critical for alloy performance in extreme environments.

Stress Corrosion Cracking in High-Strength Al-Zn-Mg-Cu Alloys

TIn high-strength Al-Zn-Mg-Cu alloys, stress corrosion cracking (SCC) is a significant concern, particularly under tensile stress in corrosive environments. The mechanism involves a combination of electrochemical behavior and dislocation dynamics. In these alloys, the presence of precipitates, such as η-phase (MgZn2), plays a key role in the SCC process. Dislocations interact with these precipitates, leading to localized strain accumulation and electrochemical potential differences at the interface, which can promote the initiation of cracks. The precipitate-matrix interface acts as a weak point where corrosion can propagate, especially in chloride-rich environments. The dislocation-aided electrochemical interactions at these interfaces accelerate crack growth by facilitating the penetration of corrosive agents, ultimately reducing the alloy’s mechanical integrity under stress. Understanding these interactions is crucial for improving the corrosion resistance and fracture toughness of Al-Zn-Mg-Cu alloys in high-performance applications.

Representative Publications and Presentations

- Impact of Intermetallic phase on pitting corrosion and high-temperature tensile properties of Al-Si-Cu-Ni alloys.
Saif Haider Kayani, Heon-Young Ha, Byung-Joo Kim, Young-Hee Cho, Hyeon-Woo Son, Jung-Moo Lee
Corrosion Science (2024) 112064.
DOI

- Dislocation-assisted localized pitting corrosion behavior of Al‒Si‒Mg‒Cu‒Mn alloy.
Saif Haider Kayani, Heon-Young Ha, Young-Hee Cho, Hyeon-Woo Son, Jung-Moo Lee
Corrosion Science 221 (2023) 111372.
DOI

- Dislocation-aided electrochemical behavior of precipitates in stress corrosion cracking of Al–Zn–Mg–Cu alloys.
Saif Haider Kayani, Sangeun Park, Kwangjun Euh, Jae Bok Seol, Jung Gi Kim, Hyokyung Sung
Materials characterization 190 (2022) 112019.
DOI

- Effect of retrogression treatment on microstructure, mechanical properties, and corrosion behavior in Al-Zn-Mg-Cu alloy.
Hyojin Hwang, Chang-Gi Lee, Saif Haider Kayani, Hyoung-Wook Kim, Je In Lee, Se-Ho Kim, Yong-Hee Jo
Journal of Materials Research and Technology 36 (2025) 10577-10590.
DOI

- Dislocation-assisted Localized Corrosion Behavior of Intermetallic particles in Al alloys.
Saif Haider Kayani, Young-Hee Cho, Heon-Young Ha, Jung-Moo Lee
The 8th International Conference on Electronic Materials and Nanotechnology for Green Environment, 2024.

- Exploring Corrosion Behavior of Al‒Si‒Mg Alloys: Role of Intermetallic Phases.
Saif Haider Kayani, Young-Hee Cho, Hyeon-Young Ha, Jung-Moo Lee
The 22nd International Nanotech Symposium, 2024.

- Exploring Corrosion Behavior of Al‒Si‒Mg Alloys: Role of Intermetallic Phases.
Saif Haider Kayani, Young-Hee Cho, Hyeon-Young Ha, Jung-Moo Lee
Global Conference on Innovation Materials (GCIM), 2024.

- Dislocation-aided Localized Pitting Corrosion of Intermetallic Particles in Al‒Si‒Mg‒Cu‒Mn Alloy.
Saif Haider Kayani, Young-Hee Cho, Ju-Hyun Sun, Lee-Cheol Ji, Jung-Moo Lee
The 20th International Microscopy Congress (IMC20), 2023.