Cu2.8Mn0.2Al 合金之相變化

Abstract

中 文 摘 要

Cu2.8Mn0.2Al合金在淬火狀態下的顯微結構為 (D03+L-J) 相的混合。其中D03 相是在淬火中經由β → B2 → D03 之連續規律化的過程而來。此外，我們發現L-J相在 a 4 <111> 的反向晶界上比在 a 2 <100>的反向晶界上更容易析出。當我們對此合金在350℃至750℃的溫度範圍內施以不同時間的時效處理後發現，此合金隨著溫度的增加其一系列相變化過程為 (D03 + L-J) → (D03 +L-J +γ2) → (B2 +γ2) → β；值得一提的是，在Cu-Mn-Al合金中，這一實驗結果從未被其他學者觀察過。此外，當此合金在450℃作16小時的時效處理後，我們觀察到γ2會在基地內析出；而隨著γ2的成長，其周圍的錳含量也隨著增加，也因此促進L-J相在γ2顆粒的周圍析出；這一實驗結果在Cu-Mn-Al合金中也從未被發現過。

Abstract

In the as-quenched condition, the microstructure of the Cu2.8Mn0.2Al alloy was the mixture of (D03+L-J) phases and the D03 phase was formed by the β → B2 → D03 continuous ordering transition during quenching. Furthermore, it was found that the L-J precipitates are energetically more favorable to form at a/4 <111> APBs than at a/2 <100> APBs. When the as-quenched alloy was aged at temperatures ranging from 350℃ to 750℃, the phase transition sequence as the aging temperature increased was found to be (D03 + L-J) → (D03 +L-J +γ2) → (B2 +γ2) → β. It is noted here that this phase transition has never been observed by other workers in the Cu-Mn-Al alloys before. When the present alloy was aged at 450℃, γ2 particles started to form within the D03 matrix. Along with the growth of the γ2 particles, the surrounding region would be enriched in manganese. The enrichment of manganese would enhance the formation of the L-J precipitates at the regions contiguous to the

γ2 particles. This feature has also never been reported by other workers in the Cu-Mn-Al alloys before.