氫微印技術(shù)(HMT,hydrogen microprint technique),也有的地方叫做“銀飾技術(shù)"(Silver decoration technique),在1981年發(fā)表的“Direct observation of hydrogen evolution in the electron microscope scale"和1985年發(fā)表的“Hydrogen microprint technique in the study of hydrogen in steels"中較早提及并應用于分析雙相不銹鋼、低碳鋼、奧氏體不銹鋼等材料的氫擴散行為,在金屬和合金材料的氫脆研究中是一個很有價值的實驗方法。下圖展示了HMT的原理——對已預充氫的試樣,放置于含AgBr顆粒的形核乳液中。金屬試樣表面擴散出來的氫將Ag離子還原為金屬Ag,在暴露一定的時間后,將試樣表面未反應的AgBr顆粒清洗掉,再用水沖洗、吹干;在SEM下觀察白色球狀Ag顆粒在金屬微觀結(jié)構(gòu)上的分布。實驗步驟:金屬試樣準備(metallographic preparation)、陰極充氫(Cathodic charging)、形核乳液制備(Nuclear emulsion coating)、清洗(Fixing)、SEM觀察(SEM observation)。其中,HMT方法理論分辨率0.04um,實驗分辨率0.25um。(數(shù)據(jù)來源:1985年發(fā)表的“Hydrogen microprint technique in the study of hydrogen in steels)2024年,Corrosion Science上發(fā)表的“Enhancement of hydrogen embrittlement resistance in 310S austentitic stainless steel through ribbon-like δ-ferrite"中采用了HMT技術(shù)。本文中具體實驗步驟如下:
(a)和(b)the principle of HMT involves a redox reaction between hydrogen atoms and Ag ions; HMT技術(shù)原理及氫原子和銀離子反應;Ag顆粒在H原子最初富集處形成;
(c-c1) the distribution characteristics of Ag particles of the S1050 specimen show that hydrogen was mianly concentated at the austenite grain boundaries奧氏體晶界。
Regions marked as c1 and c2 in the region (c) are magnified, and the inset diagram illustrates the distribution of Ag elements銀顆粒的分布。
(d-d2) the distribution characteristics of Ag particles of S1200 specimen reveal that hydrogen was primarily concentrated at the interface between the ribbon-like δ-ferrite and austentite銀顆粒在鐵素體和奧氏體界面富集。(d1) and (d2) are enlarged views of the marked areas in(d).