Mechanical property, in vitro biodegradable behavior and biocompatibility of additive manufactured biomedical Zn-0.8Cu alloy

doi:10.1016/j.metadv.2026.02.002

Abstract

Abstract:

Laser powder bed fusion (LPBF), owing to its high manufacturing precision and ability to produce patient-specific designs, has initiated a revolution in the field of biodegradable biomedical implants. However, its unique layer-by-layer building strategy inevitably introduces anisotropy in both microstructure and properties. In this study, we systematically investigated the microstructure, mechanical properties, and degradation behavior of LPBF processed Zn-0.8Cu alloys. In addition, we elucidated the underlying microstructural influence on tensile and corrosion behavior. The results demonstrated that samples built along the vertical direction exhibit a superior strength-ductility balance compared with their horizontal counterparts. The enhanced strength was primarily from the higher density of CuZn₄ nanoprecipitates in the vertical specimens, whereas cracks tended to propagate through multiple grains to consume more energy when stretched, which simultaneously enhances ductility. Meanwhile, the presence of finer grains facilitated the formation of a stable surface oxide layer, and the decreased fractions of CuZn₄ reduced the galvanic corrosion, thereby imparting higher corrosion resistance in horizontal specimens than vertical specimens. Moreover, the alloy exhibits excellent biocompatibility, supporting robust cellular proliferation. Collectively, these findings provide new insights into the process-structure-property relationships of LPBF fabricated biodegradable implants and offer guidance for their future design and optimization.

Key words: Biodegradable zinc alloys, Laser powder bed fusion, Anisotropy, Mechanical properties, Corrosion behavior

Shusheng Guo, Changri Xiong, Wen Peng, Yudong Huang, Heng Rao, Yang Liu, Yiguo Yan, Sheng Cao, Xiaojian Wang. Mechanical property, in vitro biodegradable behavior and biocompatibility of additive manufactured biomedical Zn-0.8Cu alloy[J]. Metals Advances, 2026, 41: 94-108.

Figures/Tables 20

Fig. 1. Characteristics of Zn-0.8Cu powders and schematic illustration of the LPBF fabrication process: (a) SEM image of particle morphology for Zn-0.8Cu powders, and (b) the associated particle size distribution; (c) a schematic illustration of the LPBF process, and (d) a schematic representation of the specimen layout and laser scanning in this work.

Table 1. Elemental composition of Zn-0.8Cu powders (wt%).

Zn	Cu	Fe	Pb	Ni	Cr	O	N
Bal.	0.8	0.005	0.0005	0.0009	0.0005	0.0481	0.0009

Table 2. Processing parameters for the LPBF process.

Parameter	Value
Laser power (W)	50, 60, 70, 80, 90
Scanning speed (mm/s)	600, 630, 660, 700, 730, 760, 800
Hatch spacing (µm)	60, 65, 70
Layer thickness (µm)	30
E_v (J/mm³)	29.3-68.4

Fig. 2. (a) Relative densities vs. Ev of specimens prepared in the LPBF processing optimization stage; OM images of LPBF fabricated specimens at (b) low, (c) intermediate, (d) high Ev.

Fig. 3. XRD patterns of LPBF fabricated Zn-0.8Cu alloy on horizontal and vertical orientations.

Fig. 4. Microstructure of LPBF fabricated Zn-0.8Cu alloy on horizontal and vertical orientations: (a) and (b) OM images; (c) and (d) inverse pole figures (IPF); (e) and (f) the associated pole figures (PF); (g) and (h) grain boundary maps and phase distributions, black and yellow lines denoted HAGB and LAGB; (i) and (j) the associated grain size distributions.

Fig. 5. TEM characterizations of LPBF fabricated Zn-0.8Cu alloy: BF-TEM images in the (a) horizontal and (c) vertical orientations, respectively; (b) and (d) the associated EDS spectra of nanoprecipitates highlighted by red crosses in (a) and (c), respectively; low magnification BF-TEM images showing CuZn4 precipitates in the (e) horizontal and (f) vertical specimens, respectively.

Fig. 6. Mechanical properties of LPBF Zn-0.8Cu alloy: (a) variation of microhardness as a function of Ev; (b) representative engineering stress-strain curves of specimens fabricated in horizontal and vertical orientations; SEM images showing fracture surface morphologies of (c) horizontal and (d) vertical specimens; (e) yield strength, ultimate tensile strength, and elongation to fracture of the horizontal and vertical samples, and each orientation showed the average value of 3 replicates.

Fig. 7. Comparison of the UTS and elongation at fracture obtained in this study with previously reported Zn-based alloys prepared by LPBF and/or rolling.

Fig. 8. Electrochemical behavior of LPBF fabricated Zn-0.8Cu specimens in horizontal and vertical orientations: (a) OCP curves, (b) potentiodynamic polarization curves, (c) Nyquist plots with the corresponding equivalent circuit, and (d) the associated Bode plots.

Table 3. Electrochemical parameters of LPBF fabricated Zn-0.8Cu specimens in horizontal and vertical orientations tested in Hank’s solution at 37 °C, and the averaged values were measured in three repeated tests.

Sample	OCP (V)	E_corr (V)	I_corr (µA/cm²)	CR (mm/y)
Horizontal	−0.99 ± 0.01	−1.06 ± 0.02	19.97 ± 5.01	0.30 ± 0.08
Vertical	−1.00 ± 0.01	−1.08 ± 0.01	49.40 ± 11.14	0.74 ± 0.17

Table 4. Fitted results of the EIS measurements.

Orientations	Horizontal	Vertical
R_s (Ω·cm²)	31.93 ± 0.34	32.94 ± 0.88
CPE_f (10⁻⁴·sⁿ·Ω⁻¹·cm²)	2.96 ± 0.03	1.25 ± 0.03
n_f	0.50 ± 0.01	0.59 ± 0.03
R_f (Ω·cm²)	89.54 ± 1.15	61.58 ± 1.38
CPE_dl (10⁻⁴·sⁿ·Ω⁻¹·cm²)	1.13 ± 0.04	3.34 ± 0.12
n_dl	0.77 ± 0.02	0.67 ± 0.02
R_ct (Ω·cm²)	190.9 ± 4.8	138.1 ± 4.9

Fig. 9. Degradation behavior of LPBF Zn-0.8Cu alloy: (a) variation of solution pH during immersion, (b) evolution of Zn2+ concentration as a function of immersion time, and (c) weight loss and the corresponding calculated degradation rate during the immersion tests.

Fig. 10. Degradation products of LPBF Zn-0.8Cu alloy: (a1)-(a5) evolution of surface morphologies after different immersion durations; (b) and (c) comparison of surface morphologies of samples on horizontal and vertical planes after 28 days of immersion; (d), (e1) and (e2) corrosion products with different morphologies.

Fig. 11. Analyses of degradation products: (a) XRD patterns of surface corrosion products on horizontal and vertical planes after 28 days immersion, (b) XPS survey spectra of surface corrosion products after 28 days, and (c)-(g) high-resolution XPS spectra of C 1s, O 1s, P 2p, Ca 2p and Zn 2p3/2 on the vertical plane, respectively.

Fig. 12. In vitro cytocompatibility assessment of LPBF Zn-0.8Cu alloy: (a) live/dead staining images of MC3T3-E1 cells after 1, 3, and 5 days of co-culture with control medium and 10%, 25%, 50%, and 100% extract concentrations; (b)-(d) cell viability quantified after different durations of culture.

Table 5. Orowan strengthening estimations based on nanosized CuZn4 precipitates characteristics for horizontal and vertical specimens.

Sample	G_m (GPa)	b (nm)	d_p (nm)	r (nm)	V_p (%)	Δσ_orowan (MPa)
Horizontal	38.8 [46]	0.266	32.4	16.2	3.8	99.0
Vertical	38.8 [46]	0.266	44.6	22.3	10.0	148.5

Fig. 13. Illustration of tensile crack propagation in horizontal and vertical specimens.

Fig. 14. Schematic illustrations of the corrosion mechanisms on horizontal and vertical planes.

Fig. 15. Zn2+ and Cu2+ concentrations in extraction media of different dilutions.

References 70

[1]	N.S. Manam, W.S.W. Harun, D.N.A. Shri, S.A.C. Ghani, T. Kurniawan, M.H. Ismail, M.H.I. Ibrahim, J. Alloy. Compd. 701 (2017) 698-715. DOI URL
[2]	Y.H. Li, D.Y. Jiang, R. Zhu, C.L. Yang, L.Q. Wang, L.C. Zhang, Int. J. Extreme Manuf. 7 (2024) 022002.
[3]	Y. Luo, C. Zhang, J. Wang, F.F. Liu, K.W. Chau, L. Qin, J.L. Wang, Bioact. Mater. 6 (2021) 3231-3243.
[4]	A.R. Khan, N.S. Grewal, C. Zhou, K.S. Yuan, H.J. Zhang, Z. Jun, Results Eng. 20 (2023) 101526. DOI URL
[5]	S. Amukarimi, M. Mozafari, MedComm 2 (2021) 123-144. DOI PMID
[6]	J.Z. Zhang, Z.Z. Shang, Y.B. Jiang, K. Zhang, X.G. Li, M.L. Ma, Y.J. Li, B. Ma, Regener. Biomater. 8 (2021) rbaa047. DOI URL
[7]	X.X. Shao, X. Wang, F.F. Xu, T.Q. Dai, J.G. Zhou, J. Liu, K. Song, L. Tian, B. Liu, Y.P. Liu, Bioact. Mater. 7 (2022) 154-166.
[8]	N. Mollaei, S.M. Fatemi, M.R. Aboutalebi, S.H. Razavi, W. Bednarczyk, Acta Metall. Sin.-Engl. Lett. 38 (2025) 507-525.
[9]	J. Tokarczyk, W. Koch, Molecules 30 (2025) 2742. DOI URL
[10]	X. Tong, D.C. Zhang, X.T. Zhang, Y.C. Su, Z.M. Shi, K. Wang, J.G. Lin, Y.C. Li, J.X. Lin, C.E. Wen, Acta Biomater. 82 (2018) 197-204. DOI URL
[11]	H.F. Li, H.T. Yang, Y.F. Zheng, F.Y. Zhou, K.J. Qiu, X. Wang, Mater. Des. 83 (2015) 95-102. DOI URL
[12]	S.Y. Liu, D. Kent, N. Doan, M. Dargusch, G. Wang, Bioact. Mater. 4 (2019) 8-16.
[13]	H. Huang, H. Liu, L.S. Wang, Y.H. Li, S.O. Agbedor, J. Bai, F. Xue, J.H. Jiang, Acta Metall. Sin.-Engl. Lett. 33 (2020) 1191-1200.
[14]	C. García-Mintegui, L.C. Córdoba, J. Buxadera-Palomero, A. Marquina, E. Jiménez- Piqué, M.P. Ginebra, J.L. Cortina, M. Pegueroles, Bioact. Mater. 6 (2021) 4430-4446. DOI PMID
[15]	B. Jia, H.T. Yang, Z.C. Zhang, X.H. Qu, X.F. Jia, Q. Wu, Y. Han, Y.F. Zheng, K.R. Dai, Bioact. Mater. 6 (2021) 1588-1604. DOI PMID
[16]	T.T. Wang, L. Liu, Z.X. Liu, K. Wang, R.H. Yao, X.H. Yao, R.Q. Hang, Acta Metall. Sin.-Engl. Lett. 38 (2025) 1157-1173.
[17]	H.F. Li, Y. Huang, X.J. Ji, C.E. Wen, L.N. Wang, J. Mater. Sci. Technol. 131 (2022) 48-59. DOI URL
[18]	I. Salah, I.P. Parkin, E. Allan, RSC Adv. 11 (2021) 18179-18186. DOI URL
[19]	S. Percival, Am. J. Clin. Nutr. 67 (1998) 1064S-1068S.
[20]	J.F. Collins, L.M. Klevay, Adv. Nutr. 2 (2011) 520-522. DOI PMID
[21]	J.J. Huang, Y.L. Lai, H.L. Jin, H.M. Guo, F.R. Ai, Q. Xing, X.J. Yang, D.J. Ross, J. Mater. Eng. Perform. 29 (2020) 6484-6493. DOI
[22]	X.H. Qu, H.T. Yang, B. Jia, Z.F. Yu, Y.F. Zheng, K.R. Dai, Acta Biomater. 117 (2020) 400-417. DOI URL
[23]	C. Zhou, H.F. Li, Y.X. Yin, Z.Z. Shi, T. Li, X.Y. Feng, J.W. Zhang, C.X. Song, X.S. Cui, K.L. Xu, Y.W. Zhao, W.B. Hou, S.T. Lu, G. Liu, M.Q. Li, J.Y. Ma, E. Toft, A.A. Volinsky, M. Wan, X.J. Yao, C.B. Wang, K. Yao, S.K. Xu, H. Lu, S.F. Chang, J.B. Ge, L.N. Wang, H.J. Zhang, Acta Biomater. 97 (2019) 657-670. DOI URL
[24]	S. Chowdhury, N. Yadaiah, C. Prakash, S. Ramakrishna, S. Dixit, L.R. Gupta, D. Buddhi, J. Mater. Res. Technol. 20 (2022) 2109-2172. DOI URL
[25]	A. Behjat, S. Sanaei, M.H. Mosallanejad, M. Atapour, A. Saboori, Acta Metall. Sin.- Engl. Lett. 38 (2025) 969-980.
[26]	C.J. Shuai, Z. Dong, C.X. He, W.J. Yang, S.P. Peng, Y.W. Yang, F.W. Qi, J. Mater. Res. Technol. 9 (2020) 2623-2634. DOI URL
[27]	J.B. Liu, D.K. Wang, B. Liu, N. Li, L.X. Liang, C. Chen, K.C. Zhou, I. Baker, H. Wu, J. Mater. Sci. Technol. 186 (2024) 142-157. DOI URL
[28]	G.L. Huang, G.M. He, Y. Liu, K. Huang, Addit. Manuf. 82 (2024) 104025.
[29]	C.B. Ni, J.J. Zhu, B.G. Zhang, K. An, Y.Q. Wang, D.J. Liu, W. Lu, L.D. Zhu, C.F. Liu, Virtual Phys. Prototy. 20 (2025) e2446952. DOI URL
[30]	M.N. Doğu, S. Ozer, M.A. Yalçın, K. Davut, M.A. Obeidi, C. Simsir, H. Gu, C. Teng, D. Brabazon, J. Mater. Res. Technol. 33 (2024) 5457-5481. DOI URL
[31]	ASTM G102-89 (2015)e1: Standard Practice for Calculation of Corrosion Rates and Related Information from Electrochemical Measurements, 2015.
[32]	ASTM G31-72(2004): Standard Practice for Laboratory Immersion Corrosion Testing of Metals, 2004.
[33]	ISO 10993-5:2009: Biological Evaluation of Medical Devices—Part 5: Tests for In Vitro Cytotoxicity, 2009.
[34]	Q. Liu, H.K. Wu, M.J. Paul, P.D. He, Z.X. Peng, B. Gludovatz, J.J. Kruzic, C.H. Wang, X.P. Li, Acta Mater. 201 (2020) 316-328. DOI URL
[35]	G. Buffa, A. Costa, D. Palmeri, G. Pollara, L. Fratini, CIRP J. Manuf. Sci. Technol. 52 (2024) 1-11. DOI URL
[36]	M.L. Yang, Y. Shuai, Y.W. Yang, D. Zeng, S.P. Peng, Z.J. Tian, C.J. Shuai, Virtual Phys. Prototyp. 17 (2022) 700-717. DOI URL
[37]	Y.W. Yang, M.L. Yang, C.X. He, F.W. Qi, D. Wang, S.P. Peng, C.J. Shuai, Compos. Part B 216 (2021) 393-402 (108882).
[38]	Y. Qin, P. Wen, D.D. Xia, H. Guo, M. Voshage, L. Jauer, Y.F. Zheng, J.H. Schleifenbaum, Y. Tian, Addit. Manuf. 33 (2020) 101134.
[39]	M.L. Yang, L.Y.M. Yang, S.P. Peng, F. Deng, Y.G. Li, Y.W. Yang, C.J. Shuai, Bio-Des. Manuf. 6 (2023) 103-120. DOI
[40]	Y.W. Yang, F.L. Yuan, C.D. Gao, P. Feng, L.F. Xue, S.W. He, C.J. Shuai, J. Mech. Behav. Biomed. Mater. 82 (2018) 51-60. DOI URL
[41]	C.J. Shuai, S.W. Zhong, Z. Dong, C.X. He, Y. Shuai, W.J. Yang, S.P. Peng, Mater. Charact. 190 (2022) 112054112054.
[42]	Y. Qin, P. Wen, M. Voshage, Y.Z. Chen, P.G. Schückler, L. Jauer, D.D. Xia, H. Guo, Y.F. Zheng, J.H. Schleifenbaum, Mater. Des. 181 (2019) 107937. DOI URL
[43]	H.F. Li, X.H. Xie, Y.F. Zheng, Y. Cong, F.Y. Zhou, K.J. Qiu, X. Wang, S.H. Chen, L. Huang, L. Tian, L. Qin, Sci. Rep. 5 (2015) 10719. DOI PMID
[44]	C.J. Shuai, M.L. Yang, F. Deng, Y.W. Yang, S.P. Peng, F.W. Qi, C.X. He, L.D. Shen, H.X. Liang, J. Zhejiang Univ. A 21 (2020) 876-891.
[45]	S.Y. Zhao, C. Zhou, J.X. Hou, P.P. Li, H.D. Che, Y.Z. Zheng, J.Q. Gao, Y.X. Shi, C.C. Huang, X. Li, Y.C. Lu, Y.Z. Wu, H.P. Zhou, Y.G. Li, L.N. Wang, J. Mater. Sci. Technol. 236 (2025) 245-261. DOI URL
[46]	C.X. Lan, Y.L. Hu, C.Z. Wang, W. Li, X.H. Gao, X. Lin, Addit. Manuf. 85 (2024) 104153.
[47]	B.P. Baltazar-García, L. Landa-Ruiz, R. Croche, D. Lozano, J. Reyes, G. Santos, C.T. Méndez, F. Estupiñan, C. Gaona, M.A. Baltazar-Zamora, Eur. J. Eng. Tech. Res. 10 (2025) 15-20.
[48]	S.F. Jawed, C.D. Rabadia, Y.J. Liu, L.Q. Wang, P. Qin, Y.H. Li, X.H. Zhang, L.C. Zhang, Mater. Sci. Eng. C 110 (2020) 110728. DOI URL
[49]	M.A. Buhairi, F.M. Foudzi, F.I. Jamhari, A.B. Sulong, N.A.M. Radzuan, N. Muhamad, I.F. Mohamed, A.H. Azman, W.S.W. Harun, M.S.H. Al-Furjan, Prog. Addit. Manuf. 8 (2023) 265-283. DOI
[50]	Z.H. Ren, G. Fu, F. Liu, S.L. Mao, R. Gao, J.J. Jiang, Z.S. Tang, J. Mater. Res. Technol. 32 (2024) 1672-1682. DOI URL
[51]	Y.N. Zhao, T. Ma, Z.J. Gao, Y.Y. Feng, C. Li, Q.Y. Guo, Z.Q. Ma, Y.C. Liu, Compos. Part B 266 (2023) 111040. DOI URL
[52]	P.V. Cobbinah, S. Matsunaga, Y. Yamabe-Mitarai, Adv. Eng. Mater. 25 (2023) 2300819. DOI URL
[53]	W. Bednarczyk, M. Wątroba, J. Kawałko, P. Bała, Mater. Sci. Eng. A 748 (2019) 357-366. DOI URL
[54]	Z.B. Tang, J.L. Niu, H. Huang, H. Zhang, J. Pei, J.M. Ou, G.Y. Yuan, J. Mech. Behav. Biomed. Mater. 72 (2017) 182-191. DOI URL
[55]	Z.R. Peng, T. Meiners, Y.F. Lu, C.H. Liebscher, A. Kostka, D. Raabe, B. Gault, Acta Mater. 225 (2022) 117522. DOI URL
[56]	J.M. Jiang, H. Huang, J.L. Niu, Z.H. Jin, M. Dargusch, G.Y. Yuan, Scr. Mater. 200 (2021) 113907. DOI URL
[57]	Z. Xie, Y. Dai, X. Ou, S. Ni, M. Song, Mater. Sci. Eng. A 776 (2020) 139001139001.
[58]	D.L. Wenzler, K. Bergmeier, S. Baehr, J. Diller, M.F. Zaeh, Integr. Mater. Manuf. Innov. 12 (2023) 41-51. DOI
[59]	M.S. Mohebbi, L. Husemann, A. Toenjes, D. Knoop, V. Ploshikhin, Results Eng. 27 (2025) 106730106730.
[60]	A.C. de, F. Silveira, L.T. Belkacemi, P.J. de Castro, M. Schowalter, R. Fechte-Heinen, J. Epp, Acta Mater. 283 (2025) 120488. DOI URL
[61]	Z.W. Yang, H. Liu, K.X. Ren, L.F. Ye, X.R. Zhuo, J. Ju, F. Xue, J. Bai, J.H. Jiang, Y.C. Xin, Mater. Sci. Eng. A 850 (2022) 143584. DOI URL
[62]	Z.Z. Shi, X.X. Gao, H.J. Zhang, X.F. Liu, H.Y. Li, C. Zhou, Y.X. Yin, L.N. Wang, Bioact. Mater. 5 (2020) 210-218. DOI PMID
[63]	Z. Zhang, D.L. Chen, Scr. Mater. 54 (2006) 1321-1326. DOI URL
[64]	Y.P. Lu, A.B. Liu, S.Q. Jin, J.B. Dai, Y.M. Yu, P. Wen, Y.F. Zheng, D.D. Xia, Adv. Mater. 37 (2025) 2410589. DOI URL
[65]	Z. Dong, C.J. Han, G.Q. Liu, J. Zhang, Q.L. Li, Y.Z. Zhao, H. Wu, Y.Q. Yang, J.H. Wang, J. Mater. Sci. Technol. 214 (2025) 87-104. DOI URL
[66]	M. Meng, J.Z. Wang, H.G. Huang, X. Liu, J. Zhang, Z.H. Li, J. Orthop. Transl. 42 (2023) 94-112. DOI PMID
[67]	V.C. Shunmugasamy, M. AbdelGawad, M.U. Sohail, T. Ibrahim, T. Khan, T.D. Seers, B. Mansoor, Bioact. Mater. 28 (2023) 448-466. DOI PMID
[68]	Z.Z. Shi, X.M. Li, S.L. Yao, Y.Z. Tang, X.J. Ji, Q. Wang, X.X. Gao, L.N. Wang, J. Mater. Sci. Technol. 138 (2023) 233-244. DOI URL
[69]	L. Fowler, H. Engqvist, C. Öhman-Mägi, Materials 12 (2019) 3798. DOI URL
[70]	J.L. Wang, F. Witte, T.F. Xi, Y.F. Zheng, K. Yang, Y.S. Yang, D.W. Zhao, J. Meng, Y.D. Li, W.R. Li, K.M. Chan, L. Qin, Acta Biomater. 21 (2015) 237-249. DOI URL