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Materials Science in Additive Manufacturing LPBF of Ti-Al-graded multi-materials

samples. This study also established a relationship between consistent pattern of variation, initially increasing
laser processing parameters, interface microstructure, and and then decreasing with increasing scanning speed.
mechanical properties. Notably, at a scanning speed of 2800 mm/s, the
Ti6Al4V/AlMgScZr-graded multi-material achieved
4. Conclusion a maximum compressive strength of 1531 MPa,
This paper presents a methodology for incorporating demonstrating excellent compressive performance.
a composition-graded layer (25wt% Ti6Al4V + 75wt% Acknowledgments
AlMgScZr) into the interface of Ti6Al4V/AlMgScZr
multi-material fabricated through the LPBF process. In None.
the study, the influence mechanism of the graded layer’s
laser scanning speed on crack formation, metallurgical Funding
reaction, and microstructure evolution were investigated. The authors gratefully acknowledge the funding support
The following conclusions are drawn: from National Key Research and Development Program
(i) As the scanning speed increased from 2400 mm/s to (No. 2023YFB4603300 and 2023YFB4603304), the
3000 mm/s, significant changes were observed in the National Natural Science Foundation of China (No.
surface morphologies of the graded layer in Ti6Al4V/ 52225503), the Key Research and Development Program
AlMgScZr-graded multi-material. Initially, a rough of Jiangsu Province (No. BE2022069 and No. BE2022069-
interface with cracks and pores was evident, which 1), and the National Natural Science Foundation of China
then transitioned into a relatively smoother surface for Creative Research Groups (Grant No. 51921003).
with increasing scanning speeds. At higher scanning
speeds, cracks resulted from unmelted powders were Conflict of interest
observed. The increase in scanning speed led to a The authors declare that they have no (potential)
decrease in residual thermal stress, which prevented conflicts or competing interests with any institutes,
crack formation. On the other hand, when the organizations, or agencies that might influence the
scanning speed was too high, insufficient laser energy integrity of results or objective interpretation of their
input hindered the complete melting of powders at the submitted works to disclose.
edge of the molten pool. Notably, at a scanning speed
of 2800 mm/s, the maximum density (3.24 g/cm ) and Author contributions
3
2
minimum crack area (0.067 mm ) were observed.
(ii) The TiAl was generated through a metallurgical Conceptualization: Dongdong Gu
3
reaction, resulting from the diffusion of Ti and Al Formal analysis: Hong Liu, He Sun
elements through the graded layer under the influence Funding acquisition: Dongdong Gu
of Marangoni convection. With an increase in scanning Investigation: Guangjing Huang, Kaijie Lin
speed, decreased laser energy input prevented the Methodology: Guangjing Huang
complete melting of Ti powders and their reaction Project administration: Dongdong Gu, Kaijie Lin
with Al, leading to a gradual decrease of TiAl content.
3
The morphology of TiAl was determined by the Supervision: Dongdong Gu, Kaijie Lin
3
atomic ratio of Al and Ti in the melt pool. When the Validation: Rui Wang, He Sun
atomic ratio of Al to Ti approached 3, coarse dendrites Visualization: Hong Liu
formed. However, an insufficient amount of either Writing – original draft: Hong Liu
Al or Ti atoms constrained dendrite growth, leading Writing – review & editing: Guangjing Huang, Dongdong Gu
to the development of rod-like or finer dendritic
structures. Ethics approval and consent to participate
(iii) When the scanning speed was 2800 mm/s, a gradual Not applicable.
decrease in microhardness from the Ti6Al4V layer
to the AlMgScZr layer was observed. Microhardness Consent for publication
values exhibited a stable and continuous variation
without any significant abrupt changes, attributed to the Not applicable.
presence of a strong metallurgical bond at the interface.
The compressive strength and densification behavior Availability of data
of LPBF-processed Ti6Al4V/AlMgScZr-graded multi- If required, the original data will be provided as per the
materials at different scanning speeds exhibited a submission guidelines.

Volume 3 Issue 2 (2024) 12 doi: 10.36922/msam.3088