鎂加入鋅、鈣製成鎂基材的合金材料，具有良好的生物相容性(biocompatibility)，生物可降解性(biodegradability)和生物可吸收性(bio-absorbability)，在醫用植入材料界備受矚目，如骨釘或支架。純鎂在人體中的腐蝕速率過快，而鎂、鋅、鈣三種元素會形成介金屬化合物(IMC)，提升材料的抗腐蝕能力。文獻中常見探討鎂合金腐蝕行為的傳統技術包含掃描電子顯微鏡(SEM)、X光繞射儀(XRD)和釋氫試驗(hydrogen evolution test)，然而，皆無法看到腐蝕過程之影像以及臨場成分分析。為了解鎂鋅鈣合金的抗腐蝕機制，本文將引入新穎的研究方法—液態穿透式電子顯微鏡技術(liquid TEM)，以微米至奈米(micro-to-nano)尺度的視角觀察鎂鋅鈣合金分別在水與氯化鈉水溶液中腐蝕之現象，包含臨場(in-situ)影像、成分分布變化等，特別是探討文獻中鮮少討論之鎂合金第二相(secondary phase)變化，進而推得腐蝕機制。
本研究之鎂鋅鈣合金材料由金屬中心(MIRDC)提供，包含鑄錠、粉末及粉末熱壓成型塊材，其中粉末之微觀結構較為穩定，是由介金屬化合物第二相Ca2Mg6Zn3 (IM1)呈網狀分布，將不規則形狀的鎂基材隔開，故作為腐蝕機制探討之對象。鎂鋅鈣合金粉末經DI water腐蝕後，可發現微米級的氧化鎂相，推測是鎂基材和水中的氧氣反應產生。而Ca2Mg6Zn3 (IM1)則不會被腐蝕，但可能有微量溶解，且出現因為周圍鎂基材被腐蝕而失去支撐之隨時間向外擴散的現象。
當溶液中有氯離子時，會使鎂基材被腐蝕形成易溶於水的MgCl2，亦導致Ca2Mg6Zn3 (IM1)產生變化。推測其中大部分的鎂和鈣以離子的形式存在於溶液中，鋅則形成難溶於水的非晶Zn-rich相(可能為ZnO)覆蓋在試片上，或許有機會作為披覆的鈍化層，阻擋剩餘的鎂合金與腐蝕液直接接觸，進而降低腐蝕速率。

In order to realize the corrosion mechanism of degradable Mg-Zn-Ca alloy at micro-to-nano scale, liquid TEM as a novel technique performing a liquid environment via an isolated sandwich chip structure was introduced. Galvanic corrosion, which can be considered as a kind of localized corrosion, was observed to occur in DI water and NaCl solutions due to corrosion potential difference between the Mg matrix and the secondary phase, intermetallic compound Ca2Mg6Zn3 (IM1). Moreover, IM1 was discovered that it became a Zn-rich phase after immersed in NaCl solutions. This has not been widely discussed.

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