Abstract
There is a growing demand for the ability to manufacture large-scale aluminum-steel (Al-Fe) bimetallic components for realizing the enormous advantages of advanced multi-material structures which offers effective lightweighting and increasingly smart functionalities. The formation of brittle intermetallic compounds (IMCs) at the bonding interface has been the major barrier to safety-critical applications with existing manufacturing processes, including additive manufacturing techniques. This study showed that a combination of a novel modified friction stir additive manufacturing (M-FSAM) and pre-processing surface polishing of the stainless steel enables the formation of a relative homogenously distributed nanoscale amorphous layer along the bonding interface between the 6061 Al and the 304 stainless steel. As a result, the high interfacial bonding strength of 280 MPa was achieved. Compared to the existing friction stir welding/AM processes, M-FSAM enables a significant increase in tool traverse speed and a remarkable reduction in tool cost for Al-Fe bimetallic component manufacturing. The nanoscale amorphous layer consisted of a continuous O and Mg rich layer 10–20 nm in thickness and a discontinuous Al-Fe-Si layer 50–100 nm in thickness. The O and Mg rich layer consisted of an amorphous matrix with nanocrystalline precipitates while the Al-Fe-Si layer consisted of a q-glass with some degree of crystallinity. The formation mechanism of the unique Al-Fe interfacial microstructure was analyzed in detail in this study.
Original language | English |
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Article number | 117721 |
Journal | Journal of Materials Processing Technology |
Volume | 308 |
DOIs | |
State | Published - Oct 2022 |
Externally published | Yes |
Funding
This work was partially supported by the University of Michigan College of Engineering startup grant and the National Science Foundation (NSF CMMI 2126163 ). The authors acknowledge the financial support of the University of Michigan College of Engineering and technical support from the Michigan Center for Materials Characterization. The authors also acknowledge the support of C. R. T. N. Phanuphong on equipment operation and preparation of the test specimens.
Keywords
- Amorphization mechanism
- Dissimilar metals
- Friction stir additive manufacturing
- Friction stir welding
- Interfacial amorphization
- Intermetallic compounds