鐵鋁基三元合金在H2/NH3/Ar混合氣氛下之氮化行為研究

The Nitridation Behavior of Fe-Al Base Ternary Alloys in H2/NH3/Ar Mixed Gases

本文探討鐵鋁基三元合金（含Fe-28Al-2Mo及Fe-28Al-2Cr）於H2/NH3/Ar氣氛下，溫度500～700℃間的氮化行為。研究顯示三元合金在各溫度之氮化動力學皆遵守拋物線型定律，且氮化反應速率隨添加元素不同而異。因Mo元素的原子半徑較Cr元素大，經原子置換後，基材晶格常數變大，使氮溶解度增加，因此，添加Mo的氮化反應速率比添加Cr的氮化反應速率為快。經由XRD分析合金氮化後的表層，皆以Fe3N和Fe4N之混合氮化物為主，而內層則有AlN 之形成，但無Mo或Cr之氮化物生成。

The purpose of this work is to study the nitridation behavior of Fe-Al base ternary alloys (containing Fe-28Al-2Mo and Fe-28Al-2Cr) over the temperature range 500 ~700℃ in a H2/NH3/Ar gas mixture. The nitridation kinetics followed the parabolic rate law, and the nitridation rates of the alloys were strongly dependent on ternary elements. Because the atomic radius of Mo is higher than that of Cr, the Mo-content alloy has a larger lattice constant as Mo replaced the substitional site of Fe atom, which resulted in increasing N solubility, thereby increasing nitridation rates. The nitrides formed on Fe-Al base ternary alloys consisted of mostly Fe4N, Fe3N, and minor AlN. There is no evidence to reveal the formation of Mo or Cr nitrides.