材料分析的演進

對於1980年以前的材料前輩而言，材料分析一詞尚不普遍，那時代對材料顯微結構研究分析的行為稱之為金相分析，因為主要分析的材料為金屬材料。所以，卅年以前的機械系和冶金系的學生大概幾乎都修過金相學。必做的實驗，就是切下一塊金屬材料，通過研磨、拋光等程序後，再加上適當的蝕刻，最後將試片放在光學顯微鏡下觀察，可以看到如圖2的顯微結構。通過金相學分析，研究者可以建立金屬材料強度和晶粒大小的關係，也可以看到材料內是否有析出物、雙晶、疊差、…等結構，推斷這些結構對金屬機械性質的影響。

People might not be familiar with the terminology, MA, before 1980. Before 1980, most of microstructure analyses focused on metal materials. So, work on microstructure analysis was called metallography. Students of department of mechanic engineering and department of metallurgy in colleges all took metallography courses. Everyone cut a small piece of metal, ground and polished it, then put it under a optical microscope after properly etching it. The typical image observed is like that shown in Figure 1. Researchers established relationship of strength and grain size for many metals. Studies of effect of precipitates, twins, and stacking faults …etc. on metals were popular conducted in metallurgy.

圖2. 典型光學金相照片顯示多晶材料的晶粒大小。(感謝環球檢驗科技許傳宗先生提供)

隨著電子顯微鏡的進入材料分析領域，當高能電子進入試片，和試片組成元素的原子交互作用後，產生的訊號除可形成高倍率影像外，部分訊號也提供元素種類，甚至化學鍵結的訊息。顯微結構分析不再只限於影像，微區成份訊息也可也可分析。穿透式電電鏡(TEM)更進一步提供試片的晶體結構訊息。被分析的材料也從金屬擴展到精密陶瓷(fine ceramics)，半導體，等材料，甚至部分有機材料。這時候，金相學一詞逐漸消失，材料分析一詞則逐漸崛起，最後凡是對材料或元件的顯微結構進行分析者統稱材料分析。

When electron microscopes were introduced into the field of MA, besides images of high magnification, information of elements could be extracted, so did chemical bonding state of atoms. TEM can even more take crystallography information out of nano regions. Materials of fine ceramics, semiconductor, and some organics were more and more being analyzed by electron microscopes. The terminology, metallography, was then gradually replacing by materials analysis (MA).