(中南大學(xué) 材料科學(xué)與工程學(xué)院, 長沙 410083)
摘 要: 利用相圖熱力學(xué)數(shù)據(jù)庫設(shè)計Mg-Al-Zn-Sm系合金的成分和熱處理工藝。合金經(jīng)熔煉鑄造后進行T6工藝熱處理。通過硬度測試確定合金的峰時效點，并在峰時效點進行室溫拉伸實驗。結(jié)果表明：成分為Mg-6Al- 1.3Sm-1Zn(質(zhì)量分數(shù)，%)的樣品時效后的抗拉強度(σb)為263 MPa。采用X射線衍射(XRD)和透射電子衍射(TEM)并結(jié)合X射線能譜分析方法確定合金基體為Mg-Zn固溶體，析出相為Mg17Al12與Al2Sm。借助金相光學(xué)顯微技術(shù)與掃描電鏡(SEM)對合金的微觀組織形貌進行分析，并采用熱力學(xué)計算對顯微組織的形成進行解釋。示差掃描量熱技術(shù)(DSC)測試結(jié)果表明：合金凝固過程中的相變點與計算模擬的結(jié)果吻合。
關(guān)鍵字: Mg-Al-Zn-Sm合金；相圖；沉淀強化；力學(xué)性能；熱力學(xué)計算
（School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:The alloy composition and process parameters of Mg-Al-Zn-Sm alloy were designed by using thermodynamic database. T6 heat treatment was carried out, following the melting and casting. According to hardness measurement, peak aging time was found. Tensile experiments were carried out. The results show that the tensile strength (σb) is 263 MPa in the tensile experiment to the alloy sample of the composition Mg-6Al-1.3Sm-1Zn (mass fraction, %). Mg-Zn solid solution matrix, Al2Sm and Mg17Al12 precipitates were determined in alloys by using X-ray diffraction (XRD) and transmission electronic microscopy (TEM) along with X-ray spectrum (EDX). Combined optical microscopy with scanning electronic microscopy (SEM), the microstructures of samples in casting and annealing states were observed. The experimental results were discussed based on thermodynamics. Differential scanning calorimeter (DSC) was employed to test the phase transformation points in the solidification. The experimental data are consistent with the simulation results by thermodynamic database.
Key words: Mg-Al-Sm-Zn alloy; phase diagram; precipitation strengthening; mechanical properties; thermodynamic calculation
