隨著材料科技的發展，對於合金鋼性能的要求不斷提高。錳鋁合金鋼在加入鎳元素後可提高抗氧化等特性，是很有發展潛力的合金鋼種。本研究以五元合金Fe-20 Ni-15 Mn-3.7 Al-1.0 C (wt.%)作為研究項目，將材料先做1100℃固溶處理的前處理，再分別進行600至1000℃的恆溫處理。觀察合金鋼經固溶處理及恆溫處理後的微觀結構以及推判相變化過程。
本合金鋼經固溶處理後組成為沃斯田體相基地，而晶界上可觀察到少量析出物。合金鋼經600至1000℃恆溫處理後，觀察室溫下基地均以γ相為主，基地內及晶界上同時析出富鎳鋁B2晶粒，經實驗推論B2晶粒於500℃以上應為BCC (α)結構，並於冷卻至室溫過程中發生Spinodal相分離與序化反應，在BCC晶粒內生成貧鎳鋁BCC1 (α’)相與富鎳鋁BCC2 (α’’)相的組成晶粒，其中BCC2相在冷卻過程中經序化反應轉變為為B2相，經實驗證實B2相生成溫度應低於500℃以下，其連續反應式為BCC (α)→ BCC1 (α’)+ BCC2 (α’’) → BCC1 (α’)+ B2。合金鋼於600℃至800℃恆溫處理後，沃斯田體基地與晶界析出M3C碳化物，其總反應式為γ → γ1 + α + M3C碳化物。

With the development of material technology from past age to present, the requirement for performance of alloy steel has significantly increased. The manganese-aluminum alloy will improve corrosion resistance under high temperature after adding nickel element into the alloy. As a result, the alloy of manganese-aluminum including nickel element is a material with great development potential of commodification. In this study, the five-element alloy (Fe-20Ni-15Mn-3,7Al-1.0C) (wt.%) was used as the research project, and observe the microstructure and phase change process analysis after the material finishing solution treatment (1100℃ for 1 hour, water quench) and after then finishing different temperature heat treatment (1000℃ to 600℃for 20 & 100 hour, water quench) respectively. Finally, observe the microstructure and infer the process of phase transformation.
The Fe-Ni-Mn-Al alloy performs a single Austenite phase (γ-Fe) in the base composition after solution treatment, and at the same time, a few precipitates can be observed on the base metal and grain boundary. When the alloy was subjected to different temperature heat treatment (600 to 1000℃) and was quench to room temperature by water, γphase were observed in all of the temperature, and BCC (α) grains were precipitated in the γ-based metal and in the grain boundaries. It is inferred by experiments that the B2 grains should be BCC (α) structure when the Temperature above 500°C, and spinodal decomposition and ordering reaction occur during cooling process until reaching room temperature. Nickel-aluminum-deficient BCC1 (α') phase is formed in the BCC grains composition grains with nickel-aluminum-rich BCC2 (α'') phase, in which the BCC2 phase is transformed into the B2 phase through ordering reaction during the cooling process. It has been proved by experiments that the formation temperature of the B2 phase should be lower than 500°C, and its continuous reaction of the formula is BCC (α) → BCC1 (α') + BCC2 (α'') → BCC1 (α') + B2. After the alloy steel finishing heat treatment at temperature 600°C to 800°C, M3C carbides are precipitated at the base and grain boundaries in FCC base metal, and the total reaction formula is γ → γ1 + α + M3C carbides.

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