鎂合金因具有較優良的生物力學性質、良好的生物相容性、生物可降解性能夠被人體吸收，不需要二次手術取出以減輕患者的痛苦。另外鎂合金在降解過程中能夠釋出鎂離子促進骨細胞生長，讓組織癒合等優點，適合做為生醫植入材，然其快速降解、大量析氫等缺點是目前所需要克服的問題。現今工業上所使用的鎂鋁鋅合金因為鋁離子被相關研究指出具有神經毒性，所以本研究採用自行開發不含鋁元素的新型鎂合金，加入鋅、鋯、鈣元素來強化鎂合金的機械性質以及改善其抗腐蝕能力。實驗中分別以純鎂、鎂鋅(Mg-4Zn)、鎂鋅鋯(Mg-4Zn-0.5Zr)、鎂鋅鋯鈣(Mg-4Zn-0.5Zr-0.2Ca)合金以及現今常用鎂鋅鋯合金（ZK60：Mg-6Zn-0.5Zr）作為對照組，來探討添加元素對於鎂合金之機械性質以及腐蝕特性。
本研究選用擠型材鎂鋅鋯鈣合金，以380˚C進行均質化處理，瞭解均質化處理對於材料組織的影響，並利用拉伸試驗、硬度試驗以及衝擊試驗來進行機械性質分析，且為了瞭解材料抗腐蝕性質，進行動電位極化曲線試驗以及浸泡試驗。而為緩和降解速率，並導入氧化皮膜處理來檢討熱處理材以及氧化皮膜處理材兩者之間的差異。
實驗結果顯示，均質化熱處理能夠有效的提升材料延性以及達到組織均勻化效果。添加鋅、鋯、鈣皆能夠使機械強度、延性有所提升，其中以鋅跟鈣的效益較為顯著。衝擊試驗顯示添加元素能夠提升材料韌性，其中以ZK60以及ZKX400的韌性表現最佳。
在腐蝕性質試驗中，因添加元素會使基材內部形成MgZn2以及Ca2Mg6Zn3等第二相，形成迦凡尼腐蝕的現象。經過均質化處理使得第二相分布較均勻，可以減緩腐蝕速率。浸泡後拉伸試驗中顯示鎂合金延性以及強度都會隨著浸泡時間而逐漸衰退，強度部分以Z4以及ZK40衰退程度較為緩和，而在第一周之後五組材料的延性的衰退程度最為明顯，從第二周之後趨於緩和。使用氧化皮膜處理的ZK60以及ZKX400則是能夠保有較好的強度但是有延性下降的現象。

As biomaterials, magnesium alloy has many advantages. It has good biomechanics and magnesium alloy is biodegradable. Also, magnesium alloy can release Mg2+ to stimulate regeneration of the body tissue. However, the rate of its degradation and the hydrogen evolution are problems that must be solved. Some researches show that Al may cause nerve toxicity, so we develop Mg-Zn-Zr-Ca alloy for the study. The study use pure Mg, Z4, ZK40, ZKX400 and commercial material ZK60 to focus on the effects of adding elements on the microstructure, mechanical properties and corrosion properties.
The results show that second phase distribute more uniformly after heat treatment. The heat treatment can slow down the corrosion rate. All of Zn, Zr, Ca can improve the mechanical properties of Mg alloys and Zn and Ca are more effectively. After adding elements, the toughness has improve in the impact.
The tensile test after immersion test show that the mechanical properties decay as immersion days increasing. The decay of strength of Z4 and ZK40 are slower than other materials. Decay of elongation of materials are obvious after 1-week immersion test. Starting from the second week, the decay of elongation has slow down. ZK60 and ZKX400 with oxide film have lower elongation and higher strength due to the brittleness.

1. Zheng, Y. F., Gu, X. N., and Witte, F. "Biodegradable metals." Materials Science and Engineering: R: Reports 77 (2014): 1-34.
2. Navarro, M., Michiardi, A., Castano, O., and Planell, J. A. "Biomaterials in orthopaedics." Journal of the Royal Society Interface 5.27 (2008): 1137-1158.
3. Niinomi, M. "Recent metallic materials for biomedical applications." Metallurgical and materials transactions A 33.3 (2002): 477-486.
4. Geetha, M., Singh, A. K., Asokamani, R., and Gogia, A. K. "Ti based biomaterials, the ultimate choice for orthopaedic implants–a review." Progress in materials science54.3 (2009): 397-425.
5. Cook, S. D., Walsh, K. A., and Haddad, J. R. "Interface mechanics and bone growth into porous Co-Cr-Mo alloy implants." Clinical orthopaedics and related research 193 (1985): 271-280.
6. Cao, W., and Hench, L. L "Bioactive materials." Ceramics international 22.6 (1996): 493-507.
7. Suchanek, W., and Yoshimura, M. "Processing and properties of hydroxyapatite-based biomaterials for use as hard tissue replacement implants." Journal of Materials Research13.1 (1998): 94-117.
8. Hench, L. L., and Polak, J. M. "Third-generation biomedical materials." Science 295.5557 (2002): 1014-1017.
9. Gu, X. N., and Zheng, Y. F. "A review on magnesium alloys as biodegradable materials." Frontiers of Materials Science in China 4.2 (2010): 111-115.
10. Nagels, J., Stokdijk, M., and Rozing, P. M. "Stress shielding and bone resorption in shoulder arthroplasty." Journal of shoulder and elbow surgery 12.1 (2003): 35-39.
11. Institute of Medicine (US) Standing Committee on the Scientific Evaluation of Dietary Reference Intakes. Dietary reference intakes for calcium, phosphorus, magnesium, vitamin D, and fluoride. National Academies Press (US), (1997).
12. Vormann, J. "Magnesium: nutrition and metabolism." Molecular aspects of medicine 24.1-3 (2003): 27-37.
13. Zheng, Y. Magnesium alloys as degradable biomaterials. CRC Press, (2015).
14. Staiger, M. P., Pietak, A. M., Huadmai, J., and Dias, G. "Magnesium and its alloys as orthopedic biomaterials: a review." Biomaterials 27.9 (2006): 1728-1734.
15. Watson, R. R., Preedy, V. R., and Zibadi, S, eds. Magnesium in human health and disease. Springer Science & Business Media, 2012.
16. Wang, Y. N., and Huang, J. C. "The role of twinning and untwinning in yielding behavior in hot-extruded Mg–Al–Zn alloy." Acta materialia 55.3 (2007): 897-905.
17. Song, G. "Control of biodegradation of biocompatable magnesium alloys." Corrosion science 49.4 (2007): 1696-1701.
18. Song, G., and Song, S. "A possible biodegradable magnesium implant material." Advanced Engineering Materials9.4 (2007): 298-302.
19. Avedesian, M. M., and Baker, H., eds. ASM specialty handbook: magnesium and magnesium alloys. ASM international, 1999.
20. Zhang, E., Yin, D., Xu, L., Yang, L., and Yang, K. "Microstructure, mechanical and corrosion properties and biocompatibility of Mg–Zn–Mn alloys for biomedical application." Materials Science and Engineering: C29.3 (2009): 987-993.
21. Kubasek, J., and Vojtěch, D. "Structural characteristics and corrosion behavior of biodegradable Mg–Zn, Mg–Zn–Gd alloys." Journal of Materials Science: Materials in Medicine 24.7 (2013): 1615-1626.
22. Zhang, S., Zhang, X., Zhao, C., Li, J., Song, Y., Xie, C., Tao, H., Zhang, Y., He, Y., Jiang, Y., and Bian, Y. "Research on an Mg–Zn alloy as a degradable biomaterial." Acta biomaterialia 6.2 (2010): 626-640.
23. Gandel, D. S., Easton, M. A., Gibson, M. A., Abbott, T., and Birbilis, N. "The influence of zirconium additions on the corrosion of magnesium." Corrosion Science 81 (2014): 27-35.
24. Sun, M., Wu, G., Wang, W., and Ding, W. "Effect of Zr on the microstructure, mechanical properties and corrosion resistance of Mg–10Gd–3Y magnesium alloy." Materials Science and Engineering: A 523.1-2 (2009): 145-151.
25. Hirai, K., Somekawa, H., Takigawa, Y., and Higashi, K. "Effects of Ca and Sr addition on mechanical properties of a cast AZ91 magnesium alloy at room and elevated temperature." Materials Science and Engineering: A 403.1-2 (2005): 276-280.
26. Yin, P., Li, N. F., Lei, T., Liu, L., and Ouyang, C. "Effects of Ca on microstructure, mechanical and corrosion properties and biocompatibility of Mg–Zn–Ca alloys." Journal of Materials Science: Materials in Medicine 24.6 (2013): 1365-1373.
27. Zhang, E., and Yang, L. "Microstructure, mechanical properties and bio-corrosion properties of Mg–Zn–Mn–Ca alloy for biomedical application." Materials Science and Engineering: A 497.1-2 (2008): 111-118.
28. Song, G.L., and Atrens, A. "Corrosion mechanisms of magnesium alloys." Advanced engineering materials 1.1 (1999): 11-33.
29. Zeng, R. C., Zhang, J., Huang, W. J., Dietzel, W., Kainer, K. U., Blawert, C., and Wei, K. E. "Review of studies on corrosion of magnesium alloys." Transactions of Nonferrous Metals Society of China 16 (2006): s763-s771.
30. Song, G., Atrens, A., and Dargusch, M. "Influence of microstructure on the corrosion of diecast AZ91D." Corrosion science 41.2 (1998): 249-273.
31. Lee, J. Y., Han, G., Kim, Y. C., Byun, J. Y., Jang, J. I., Seok, H. K., and Yang, S. J. "Effects of impurities on the biodegradation behavior of pure magnesium." Metals and Materials International15.6 (2009): 955-961.
32. Gray, J., and Luan, B. "Protective coatings on magnesium and its alloys—a critical review." Journal of alloys and compounds 336.1-2 (2002): 88-113.
33. Wu, H. L., Cheng, Y. L., Li, L. L., Chen, Z. H., Wang, H. M., and Zhang, Z. "The anodization of ZK60 magnesium alloy in alkaline solution containing silicate and the corrosion properties of the anodized films." Applied Surface Science 253.24 (2007): 9387-9394.
34. Chiu, K. Y., Wong, M.H., Cheng, F.T., and Man, H.C. "Characterization and corrosion studies of fluoride conversion coating on degradable Mg implants." Surface and Coatings Technology 202.3 (2007): 590-598.
35. Gao, X., and Nie, J. F. "Characterization of strengthening precipitate phases in a Mg–Zn alloy." Scripta Materialia 56.8 (2007): 645-648.
36. Fung, Y.C. Biomechanics: mechanical properties of living tissues. Springer Science & Business Media, (2013).