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Materials Science in Additive Manufacturing Crack-free AA7075 with Zr modification via LPBF

Figure 11 displays the morphology of cracks in Data curation: Wenhui Yu, Xuhui Zhang, Yetao Sun
AA7075 samples fabricated at VED 82 J/mm without Formal analysis: Wenhui Yu, Zhen Xiao, Xuhui Zhang,
3
and with 1 w.t.% Zr addition, respectively. The crack in Yongling Wu, Hongyu Zheng
Figure 11A is wide and smooth-edged along the building
direction, while the one in Figure 11B is curved, passing Funding acquisition: Wenhui Yu, Zhen Xiao, Hongyu
through the intergranular area. The corresponding EDS Zheng
line scans display the elemental distribution of silicon Investigation: Wenhui Yu, Xuhui Zhang, Yetao Sun
near the cracks. Concentration of silicon detected near the
cracks indicates that this minor element plays a significant Methodology: Wenhui Yu, Zhen Xiao, Xuhui Zhang, Yetao
role in increasing the susceptibility to cracking, consistent Sun, Peng Xue, Shuai Tan, Yongling Wu, Hongyu Zheng
with the literature . In Zr-modified parts, silicon would Project administration: Wenhui Yu, Zhen Xiao, Peng Xue,
[42]
Shuai Tan, Yongling Wu, Hongyu Zheng
still segregate to the grain boundaries and may weaken Resources: Xuhui Zhang, Yetao Sun
the crack resistance. However, the distribution of silicon
is more homogenous as fine grains result in more grain Supervision: Wenhui Yu, Zhen Xiao, Peng Xue, Shuai Tan,
boundaries. Therefore, the effects of silicon on cracks are Yongling Wu, Hongyu Zheng
suppressed. Validation: Wenhui Yu, Zhen Xiao, Yongling Wu, Hongyu
Zheng
4. Conclusion Visualization: Wenhui Yu, Xuhui Zhang
Crack-free AA7075 printed parts were obtained with Writing – original draft: Wenhui Yu
elemental Zr addition. Fine equiaxed grains tend to Writing – review & editing: Wenhui Yu, Zhen Xiao, Xuhui
form with VED above 76 J/mm . Crack-free AA7075 Zhang, Yongling Wu, Hongyu Zheng
3
components were obtained with VED above 82 J/mm .
3
The formation of fine equiaxed grains can be attributed References
to the Al Zr (the nuclei) and the limited grain growth.
3
The formation of dendritic skeleton accompanied by 1. Zhang D, Qiu D, Gibson MA, et al., 2019, Additive
sufficient liquid feeding at the later stage results in a crack manufacturing of ultrafine-grained high-strength titanium
alloys. Nature, 576: 91–95.
reduction. Due to the deterioration of the molten pool,
the viscosity by the unmelted Zr particles and the number https://doi.org/10.1038/s41586-019-1783-1
of spherical pores tends to increase. However, with a VED 2. Wei C, Li L, 2021, Recent progress and scientific challenges
above 82 J/mm , the porosity decreased with the ease of in multi-material additive manufacturing via laser-based
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melt fluidity. powder bed fusion. Virtual Phys Prototyp, 16: 347–371.
Acknowledgments https://doi.org/10.1080/17452759.2021.1928520
3. Sing SL, Huang S, Goh GD, et al., 2021, Emerging metallic
The authors express their gratitude to Dr. Wuhong Xin and systems for additive manufacturing: In-situ alloying and
Dr. Liu Feng from Analytical Testing Center, Shandong multi-metal processing in laser powder bed fusion. Prog
University of Technology, for their assistance in the Mater Sci, 119: 100795.
characterization of the samples.
https://doi.org/10.1016/j.pmatsci.2021.100795
Funding 4. Zhou Y, Wang J, Yang Y, et al., 2022, Laser additive
manufacturing of zinc targeting for biomedical application.
This work was supported by the financial support from Int J Bioprinting, 8: 501.
China Postdoctoral Science Foundation (grant numbers
2020M672131, 2021M690493), and the Shandong Natural http://dx.doi.org/10.18063/ijb.v8i1.501
Science Foundation (grant number ZR2020QE030). 5. Zhang Y, Attarilar S, Wang L, et al., 2021, A review on design and
mechanical properties of additively manufactured NiTi implants
Conflict of interest for orthopedic applications. Int J Bioprinting, 7: 340–340.
No potential conflict of interest was reported by the http://dx.doi.org/10.18063/ijb.v7i2.340
authors. 6. Gu D, Ma C, Dai D, et al., 2021, Additively manufacturing-
enabled hierarchical NiTi-based shape memory alloys
Author contributions with high strength and toughness. Virtual Phys Prototyp,

Conceptualization: Wenhui Yu, Zhen Xiao, Xuhui Zhang, 16(Suppl 1): S19–S38.
Yongling Wu, Hongyu Zheng https://doi.org/10.1080/17452759.2021.1892389

Volume 1 Issue 1 (2022) 9 https://doi.org/10.18063/msam.v1i1.4