(1. 中南大學(xué) 材料科學(xué)與工程學(xué)院，長沙 410083；
2. 蘇州大學(xué) 高性能金屬結(jié)構(gòu)材料研究院，蘇州 215137)
摘 要: 本文研究了在25 ℃和250 ℃條件下不同Cr、Mn質(zhì)量比Al-0.9Mg-1.1Si合金的組織和力學(xué)性能，對鑄錠進行550 ℃、10 h均勻化隨后進行水淬，再加熱到540 ℃條件下進行熱壓縮變形，隨即進行180 ℃、6 h時效處理得到實驗樣品，分別在25 ℃和250 ℃進行拉伸試驗，最后對合金顯微組織進行了分析。結(jié)果表明：在25 ℃條件下，Cr、Mn質(zhì)量比為0.1時，屈服強度達到峰值389 MPa；在250 ℃時，Cr、Mn質(zhì)量比為0.3時，達到峰值293 MPa。選取Cr、Mn質(zhì)量比為0.3能夠使合金高溫強度最大，同時室溫強度也較高。析出相、織構(gòu)和小角度晶界都對合金強度產(chǎn)生了不同程度的影響，但是不同溫度下三者對強度的影響強弱顯示出差異。在25 ℃時，織構(gòu)對合金強度的影響起主要作用，而在250 ℃時，小角度晶界對合金強度的影響起主要作用。
關(guān)鍵字: Al-Mg-Si合金；力學(xué)性能；析出相；織構(gòu)；小角度晶界
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. High-Performance Metal Structural Materials Research Institute, Soochow University, Suzhou 215137, China）
Abstract:The microstructure and mechanical properties of Al-Mg-Si alloy with different Cr-Mn mass ratios at 25 ℃ and 250 ℃ were studied. The ingot was homogenized at 550 ℃ for 10 h, then water quenched, and deformed by hot compression at 540 ℃. After that, age treatment was carried out at 180 ℃ for 6 h to get ready for the tensile test at 25 ℃ and 250 ℃. Finally, the microstructure of the alloy was analyzed. The results show that the yield strength reaches the peak value of 389 MPa when Cr-Mn mass ratio is 0.1 at 25 ℃. At 250 ℃, the yield strength reaches the peak value of 293 MPa when the ratio is 0.3. The optimal Cr-Mn mass ratio is confirmed to be 0.3, which can maximize the alloy''''s high temperature strength while the room temperature strength can be retained as well. The precipitated phase, texture and low angle grain boundary (LAGB)all have different effects on the strength of the alloy, but shows difference at 25 ℃ and 250 ℃. At 25 ℃, the texture plays a major role in the alloy strength while the effect of LAGB on the alloy strength plays a major role at 250 ℃.
Key words: Al-Mg-Si alloy; mechanical property; precipitation; texture; low angle grain boundary
