Impact Factor:

8.0

DOI number:

10.1016/j.msea.2026.149724

Journal:

Materials Science and Engineering: A

Key Words:

In-situ TEM; Crack propagation; Aluminum alloy; DispersoidsPrecipitates

Abstract:

Secondary phases play crucial roles in the strengthening and toughening of aluminum alloys. Compared with the well-known impeding effects of the secondary phases on dislocations, their roles in crack propagation remain obscure. In this work, by using in-situ TEM, we investigated the roles of secondary phases during the crack propagation process in a high-strength Al-Zn-Mg-Cu alloy. It was revealed that crack propagation modes depended on whether leading dislocations near the crack tip bypass or shear through the secondary phases. The secondary phases could pin dislocations and passivate the crack tip; consequently, cracks were deflected by large dispersoids or sheared through fine precipitates like the GPⅡ (Guinier-Preston zone II). Under quasi-static loading, in-situ observations showed that discontinuous cracks preferentially nucleated at the interfaces between the secondary phases and matrix, presumably through segregation of over-saturated vacancies—a phenomenon further explained by density functional theory calculations on the vacancy formation energies. The findings provide insights into the roles of different secondary phases in crack propagation.

Co-author:

Xiang Wang, Yuan Ma, Luning Wang

First Author:

Lei Jiang

Indexed by:

Journal paper

Correspondence Author:

Yang He, Jianxin Xie

Discipline:

Engineering

Document Type:

J

Page Number:

149724

Translation or Not:

no

Date of Publication:

2026-01-02

Included Journals:

SCI

Links to published journals:

https://www.sciencedirect.com/science/article/pii/S0921509326000043