(1. 太原工業(yè)學院 機械工程系，太原 030008；
2. 晉中學院 材料科學與工程系，晉中 030600；
3. 哈爾濱工程大學 材料科學與化學工程學院，哈爾濱 150001；
4. Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-0812, Japan；
5. 清華大學 機械工程系 摩擦學國家重點實驗室，北京 100084)
摘 要: 采用光學顯微鏡(OM)、X射線衍射分析(XRD)、帶有能譜儀(EDS)的掃描電子顯微鏡(SEM)、透射電子顯微鏡(TEM)和力學性能測試等方法，研究了壓射速度和壓射比壓對RE(Ce和Y)、Sr和AlTiB復合變質的AZ91D壓鑄鎂合金相機殼體毛坯件的微觀組織和力學性能的影響。結果表明：隨著壓射速度和壓射比壓的增加，合金的強度先增大后減小、伸長率先減小后增加，由此得到優(yōu)化的壓鑄工藝參數(shù)為澆鑄溫度680 ℃、壓射速度6 m/s和壓射比壓90 MPa。RE、Sr和AlTiB復合變質顯著細化AZ91D合金的α-Mg晶粒和Mg17Al12相，同時在基體中引入了細小彌散的TiB2、Al11Ce3、Al2Y和Al10Ce2Mn7相，它們的協(xié)同強化作用顯著提升了合金的強度。因此，變質的合金獲得了最優(yōu)的力學性能：抗拉強度為287 MPa，屈服強度為196 MPa，伸長率為4.7%。
關鍵字: 壓射速度；壓射比壓；微觀結構；力學性能；Al-5Ti-B
（1. Department of Mechanical Engineering, Taiyuan Institute of Technology, Taiyuan 030000, China;
2. Department of Materials Science and Engineering, Jinzhong University, Jinzhong 030600, China;
3. Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, Harbin Engineering University, Harbin 150001, China;
4. Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-0812, Japan;
5. State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China）
Abstract:The influences of the injection speed and injection specific pressure on the microstructure and mechanical properties of the camera body of modified AZ91D die casting magnesium alloy with RE(Ce and Y), Sr and AlTiB was studied using optical microscope (OM), X-ray diffraction (XRD), scanning electron microscope (SEM) with energy dispersive spectrometer (EDS), transmission electron microscope (TEM) and mechanical properties test. The results show that the alloy strength increases, but the elongation decreases with increasing the injection speed and injection specific pressure, and thus the optimal die-casting parameter including casting temperature of 680 ℃, injection speed of 6 m/s and injection specific pressure of 90 MPa are obtained. Co-additions of RE, Sr and AlTiB into AZ91 alloy significantly refine α-Mg grains and Mg17Al12 phases, and introduce fine TiB2, Al11Ce3, Al2Y, and Al10Ce2Mn7 phases dispersed in the matrix, which generates a synergistic hardening effect to enhance strength. As a result, the modified alloy achieves optimal mechanical properties, such as the ultimate tensile strength of 287 MPa, yield strength of 196 MPa and elongation of 4.7%.
Key words: injection speed; injection specific pressure; microstructures; mechanical properties; Al-5Ti-B
