Abstract
Alloy design strategies in additive manufacturing (AM) to achieve grain refinement and terminal eutectic solidification have been introduced to engineer Al alloys having microstructural hierarchy and heterogeneity. Such alloy design strategies enable crack-free builds with an expanded AM processing window and pushed the strength limit in Al alloys. However, fatigue performance of Al alloys made by AM is restricted by the presence of process induced defects and its stochasticity. In this work, tensile and high cycle fatigue (HCF) behavior of a novel Al-Ni-Ti-Zr alloy with a heterogeneous microstructure is studied in the as-built condition, supplemented by detailed microstructural and mechanical characterization. Excellent strength-ductility synergy of 342 MPa and 16% failure strain achieved in the alloy was associated with the microstructural attributes that pertain to the novel alloy. Additionally, the alloy showed excellent HCF performance with a fatigue endurance limit to ultimate tensile strength ratio of 0.29 in flexural fatigue mode. The study revealed the existence of multiple crack retardation mechanisms and favorable crack propagation pathways through the fine-grained regions which enabled good fatigue performance to the alloy. Further, a probabilistic model has been used to estimate the fatigue life of the alloy as a function of the stochastic microstructure by utilizing the statistical distribution of pores, solid-state inclusions, and grains in the AM Al alloy. The model parametric trends are consistent with the experimental observations.
| Original language | English |
|---|---|
| Article number | 103380 |
| Journal | Additive Manufacturing |
| Volume | 62 |
| DOIs | |
| State | Published - Jan 25 2023 |
| Externally published | Yes |
Funding
The work is a part of the research sponsored by the Office of Naval research under the ONR Award #N00014–17-1–2559 . Authors thank Materials Research Facility, and Advanced Materials and Manufacturing Processes Institute, University of North Texas, Denton for access to electron microscopes and X-ray microscopy, respectively. The work is a part of the research sponsored by the Office of Naval research under the ONR Award #N00014–17-1–2559. Authors thank Materials Research Facility, and Advanced Materials and Manufacturing Processes Institute, University of North Texas, Denton for access to electron microscopes and X-ray microscopy, respectively.
| Funders | Funder number |
|---|---|
| Materials Research Facility, and Advanced Materials and Manufacturing Processes Institute | |
| Office of Naval Research | 00014–17-1–2559 |
| University of North Texas |
Keywords
- Additive manufacturing
- Aluminum alloys
- Heterogeneous microstructure
- High cycle fatigue
- Probabilistic modeling
