- 學位論文
鐵-4鉻-18鎳- 20鈷-0.15碳合金相變化
Phase Transformations on Fe-4Cr-18Ni-20Co-0.15C Alloy
摘要
本文係利用光學顯微鏡(OM)、掃描式電子顯微鏡(SEM)、穿透式電子顯微鏡（TEM）、X光繞射分析儀與硬度機等分析技術，探討鐵-18鎳-20鈷-4鉻-0.15碳合金之顯微結構與機械性質。研究結果，如下所述： 合金試片經由固溶溫度950~1000℃/10~100分鐘，硬度值呈現穩定狀態約為Hv390~425；不同時間固溶溫度1050~1100℃，硬度值隨著時間增加呈現遞減現象。 合金試片經固溶處理後經450℃/10000分鐘長時間時效處理發現：超晶格點B2相，晶格常數a=0.282nm、DOa之δ相，晶格常數a=0.513nm以及有兩個方位的ω相，晶格常數a=0.291nm，c=0.473nm，c/a=1.625。B2相、ω相及δ相析出有強化現象，硬度值有最高值Hv551.55。 合金試片經由固溶後，250℃時效處理硬度值沒有改變；經由450℃時效處理，發現有多相析出硬化現象，硬度有最高值；經由550℃~750℃時效處理沃斯田鐵相漸形成，硬度值隨著時間增加呈現遞減現象。 關鍵字：顯微結構、超晶格、沃斯田鐵、晶格常數
並列摘要
The topic of the present studies is to investigate the microstructures and mechanical properties of the Fe-4Cr-18Ni-20Co-0.15C alloy by using of OM, SEM, TEM, XRD and hardness test. Some results are described as following: Being solution treated in the range of 950-1000℃/10~100 minutes, the hardness showed a steady state of about Hv 390~425;being solution treated in the range of 1050~1100℃, the value of hardness is decreasing with the temperature increased. Alloy specimens after solution treatment by 450℃/10000 minutes long aging found that: Superlattice point of B2 phase, the lattice constant a = 0.282nm;found DOa the δ phase, lattice constant a = 0.513nm;there are two directions of the ω phase,lattice constant a=0.291,c=0.473nm,c/a=1.625.B2 phase, ω-phase and δ phase precipitation are intensification, hardness values are the most high value Hv551.55. After the sample solution by alloys, 250 ℃ aging hardness did not change; by 450 ℃ aging treatment, found that more precipitation hardening phase, the highest value of hardness; by 550 ℃~750 ℃ aging austenite phase gradually formation. The valve of hardness is decreasing with the temperature increased. Keywords：Microstructure, Superlattice, Austenite, Lattice parameter