固溶工艺和纳米SiC添加对快冷AZ91镁合金组织及性能的影响
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摘要
采用铜模喷铸快冷法制备了添加纳米SiC的AZ91镁合金试样,研究不同固溶工艺对其组织及性能的影响。结果表明:铜模激冷与纳米SiC的添加可共同促进快冷镁合金的凝固组织发生细化,形成细小均匀的粒状晶形貌。经320℃等温处理8 h后,快冷AZ91+2 mass%纳米SiC合金发生不完全固溶现象,晶界处存在大量β-Mg_(17)Al_(12)相,同时晶粒内部形成弥散分布的沉淀析出相。随固溶温度提高,原子扩散速率的增加有利于β相向α-Mg基体中溶入,经370℃/4 h等温热处理后固溶效果明显,非平衡凝固组织基本转变为多边形等轴晶形貌。当固溶温度进一步升高到400℃时快冷镁合金中可获得单相固溶体组织,同时纳米SiC的存在有效提高了细晶组织的热稳定性,快冷合金的平均晶粒尺寸仅为9μm,高温晶粒长大行为得到有效抑制。
The samples of AZ91 magnesium alloy with nano SiC were prepared by rapid cooling method of copper mold spray casting, and the effect of different solution processes on microstructure and properties of the AZ91 magnesium alloy was studied. The results show that the copper mould chilling and the addition of nano SiC can promote the refinement of solidified microstructure of the rapid cooled magnesium alloys, resulting in the formation of fine and uniform grain morphology. After isothermal treatment at 320 ℃ for 8 h, the rapidly cooled AZ91+2 mass% nano SiC alloy exhibits incomplete solution, and there are a large number of β-M_g17 Al_(12) phases at grain boundaries, and a precipitated phase with dispersive distribution in the grains is formed at the same time. With the increase of solution temperature, the increase of atomic diffusion rate is favorable to the dissolution of β phase in α-Mg matrix. After isothermal heat treatment at 370 ℃ for 4 h, the solution effect is obvious, and the nonequilibrium solidification microstructure is transformed into polygonal equiaxed crystal morphology. The single-phase solid solution structure can be obtained when the solution temperature is increased to 400 ℃, and the thermal stability of fine grain microstructure can be effectively improved by the existence of nano SiC, the average grain size of the rapidly cooled alloy is only 9 μm, and the grain growth behavior at high temperature is effectively suppressed.
The samples of AZ91 magnesium alloy with nano SiC were prepared by rapid cooling method of copper mold spray casting, and the effect of different solution processes on microstructure and properties of the AZ91 magnesium alloy was studied. The results show that the copper mould chilling and the addition of nano SiC can promote the refinement of solidified microstructure of the rapid cooled magnesium alloys, resulting in the formation of fine and uniform grain morphology. After isothermal treatment at 320 ℃ for 8 h, the rapidly cooled AZ91+2 mass% nano SiC alloy exhibits incomplete solution, and there are a large number of β-M_g17 Al_(12) phases at grain boundaries, and a precipitated phase with dispersive distribution in the grains is formed at the same time. With the increase of solution temperature, the increase of atomic diffusion rate is favorable to the dissolution of β phase in α-Mg matrix. After isothermal heat treatment at 370 ℃ for 4 h, the solution effect is obvious, and the nonequilibrium solidification microstructure is transformed into polygonal equiaxed crystal morphology. The single-phase solid solution structure can be obtained when the solution temperature is increased to 400 ℃, and the thermal stability of fine grain microstructure can be effectively improved by the existence of nano SiC, the average grain size of the rapidly cooled alloy is only 9 μm, and the grain growth behavior at high temperature is effectively suppressed.
引文
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[17] 夏鹏举,蒋百灵,张菊梅,等.Mg-Al系镁合金离异共晶β相的研究[J].特种铸造及有色合金,2007,27(5):360-363.XIA Peng-ju,JIANG Bai-ling,ZHANG Ju-mei,et al.Divorced eutectic β phase in Mg-Al series magnesium alloys[J].Special Casting and Nonferrous Alloys,2007,27(5):360-363.
[18] 李正,吴圣川,徐道荣,等.激光熔修AZ31B镁合金焊趾区材料的疲劳性能[J].失效分析与预防,2011,6(4):209-212.LI Zheng,WU Sheng-chuan,XU Dao-rong,et al.Investigation of fatigue property of welded toes on magnesium AZ31B alloy by laser dressing method[J].Failure Analysis and Prevention,2011,6(4):209-212.
[19] 胡耀波,杨生伟,姚青山,等.挤压比及Mn含量对Mg-10Gd-6Y-1.6Zn-XMn镁合金组织和性能的影响[J].稀有金属材料与工程,2017,46(1):135-142.HU Yao-bo,YANG Sheng-wei,YAO Qing-shan,et al.Effects of extrusion ratio and Mn content on microstructure and properties of Mg-10Gd-6Y-1.6Zn-XMn magnesium alloy[J].Rare Metal Materials and Engineering,2017,46(1):135-142.
[20] 陈亮,肖代红,耿正伟,等.固溶温度对挤压态Mg-13Al-6Zn-4Cu合金组织与性能的影响[J].粉末冶金材料科学与工程,2016,21(3):463-469.CHEN Liang,XIAO Dai-hong,GENG Zheng-wei,et al.Effects of solid-solution temperature on microstructure and properties of as-extruded Mg-13Al-6Zn-4Cu alloy[J].Materials Science and Engineering of Powder Metallurgy,2016,21(3):463-469.
[21] 马颖,董海荣,张玉福,等.部分固溶处理对AZ91D镁合金微观组织及力学性能的影响[J].兰州理工大学学报,2015,41(6):1-5.MA Ying,DONG Hai-rong,ZHANG Yu-fu,et al.Effect of partial solid-solution treatment on microstructure and mechanical properties of AZ91D magnesium alloy[J].Journal of Lanzhou University of Technology,2015,41(6):1-5.
[22] 黄正华,郭学锋,张忠明.快速凝固AZ91D镁合金组织的研究[J].材料热处理学报,2005,26(1):32-36.HUANG Zheng-hua,GUO Xue-feng,ZHANG Zhong-ming.Study on microstructures of rapidly solidified AZ91D magnesium alloy[J].Transactions of Materials and Heat Treatment,2005,26(1):32-36.
[2] 徐玉磊,张奎,李兴刚,等.热处理对压铸AZ91D合金组织及硬度的影响[J].材料热处理学报,2012,33(11):63-67.XU Yu-lei,ZHANG Kui,LI Xing-gang,et al.Effects of heat treatment on microstructure and hardness of die-casting AZ91D alloy[J].Transactions of Materials and Heat Treatment,2012,33(11):63-67.
[3] 金伟男,张贵锋,曾祥,等.采用Al及Al-12Si中间层的AZ31B镁合金TLP接头的组织与性能[J].失效分析与预防,2013,8(1):25-29.JIN Wei-nan,ZHANG Gui-feng,ZENG Xiang,et al.Microstructure and mechanical properties of magnesium alloy AZ31B TLP joints using Al and Al-12Si interlayer[J].Failure Analysis and Prevention,2013,8(1):25-29.
[4] 周吉学,汪彬,童文辉,等.Sr对AZ91D镁合金枝晶生长和相析出的影响[J].金属学报,2007,43(11):1171-1175.ZHOU Ji-xue,WANG Bin,TONG Wen-hui,et al.Effect of strontium addition on dendrite growth and phase precipitation in AZ91D magnesium alloy[J].Acta Metallurgica Sinica,2007,43(11):1171-1175.
[5] 沙桂英,徐永波,于涛,等.AZ91镁合金的动态应力-应变行为及其应变率效应[J].材料热处理学报,2006,27(4):77-81.SHA Gui-ying,XU Yong-bo,YU Tao,et al.Dynamic stress-strain behavior of AZ91 magnesium alloy and its dependence on strain rate[J].Transactions of Materials and Heat Treatment,2006,27(4):77-81.
[6] 赵源华,陈云贵,唐永柏,等.Nd和Ce对AZ91镁合金组织和力学性能的影响[J].特种铸造及有色合金,2009,29(1):69-72.ZHAO Yuan-hua,CHEN Yun-gui,TANG Yong-bai,et al.Effects of Nd and Ce on microstructure and mechanical properties of AZ91 magnesium alloy[J].Special Casting and Nonferrous Alloys,2009,29(1):69-72.
[7] 王长义.AZ91HP镁合金疲劳裂纹扩展行为与断裂机理[J].失效分析与预防,2015,10(2):87-91.WANG Chang-yi.Fatigue crack propagation behavior and mechanism of AZ91HP magnesium alloy[J].Failure Analysis and Prevention,2015,10(2):87-91.
[8] Liu F,Yang G C.Rapid solidification of highly undercooled bulk liquid superalloy recent developments future directions[J].International Materials Reviews,2006,51(3):145-170.
[9] Chang J,Wang H P,Zhou K,et al.Rapid dendritic growth and solute trapping within undercooled ternary Ni-5%Cu-5%Mo alloy[J].Applied Physics A,2012,109(1):139-143.
[10] Hu Q D,Zhou Z,Yang L,et al.Orientation relationship between magnetic domains and twins in Ni52Fe17Ga27Co4 magnesium alloy[J].Metallurgical Materials Transaction A,2017,48:2675-2682.
[11] Bai J,Sun Y S,Xue F,et al.Microstructures and creep properties of Mg-4Al-(1-4) La alloys produced by different casting techniques[J].Materials Science and Engineering A,2012,552:472-480.
[12] 盛绍顶.快速凝固AZ91镁合金及其颗粒增强复合材料的研究[D].长沙:湖南大学,2008.SHENG Shao-ding.Research on rapidly solidified AZ91 magnesium alloy and composite reinforced by ceramic particles[D].Changsha:Hunan University,2008.
[13] 姜向东,陈体军,马颖,等.SiC对AZ91D镁合金晶粒细化效果的影响[J].特种铸造及有色合金,2009,29(8):763-766.JIANG Xiang-dong,CHEN Ti-jun,MA Ying,et al.Effects of SiC on the grain refinement in AZ91D magnesium alloy[J].Special Casting and Nonferrous Alloys,2009,29(8):763-766.
[14] Nie K B,Wang X J,Hu X S,et al.Microstructure and mechanical properties of SiC nanoparticles reinforced magnesium matrix composites fabricated by ultrasonic vibration[J].Materias Science and Engineering A,2011,528:5278-5282.
[15] Wang Z H,Wang X D,Zhao Y X,et al.SiC nano-particles reinforced magnesium matrix composites fabricated by ultrasonic method[J].Transaction of Nonferrous Metals Society of China,2010,20(s1):1029-1032.
[16] 杨伟,殷海眯,商景利,等.SiC颗粒参与下快冷镁合金异质形核与高温晶粒长大[J].中国有色金属学报,2017,27(2):243-250.YANG Wei,YIN Hai-mi,SHANG Jing-li,et al.Heterogeneous nucleation and grain growth at high temperature for quenched magnesium alloy containing SiC particle[J].The Chinese Journal of Nonferrous Metals,2017,27(2):243-250.
[17] 夏鹏举,蒋百灵,张菊梅,等.Mg-Al系镁合金离异共晶β相的研究[J].特种铸造及有色合金,2007,27(5):360-363.XIA Peng-ju,JIANG Bai-ling,ZHANG Ju-mei,et al.Divorced eutectic β phase in Mg-Al series magnesium alloys[J].Special Casting and Nonferrous Alloys,2007,27(5):360-363.
[18] 李正,吴圣川,徐道荣,等.激光熔修AZ31B镁合金焊趾区材料的疲劳性能[J].失效分析与预防,2011,6(4):209-212.LI Zheng,WU Sheng-chuan,XU Dao-rong,et al.Investigation of fatigue property of welded toes on magnesium AZ31B alloy by laser dressing method[J].Failure Analysis and Prevention,2011,6(4):209-212.
[19] 胡耀波,杨生伟,姚青山,等.挤压比及Mn含量对Mg-10Gd-6Y-1.6Zn-XMn镁合金组织和性能的影响[J].稀有金属材料与工程,2017,46(1):135-142.HU Yao-bo,YANG Sheng-wei,YAO Qing-shan,et al.Effects of extrusion ratio and Mn content on microstructure and properties of Mg-10Gd-6Y-1.6Zn-XMn magnesium alloy[J].Rare Metal Materials and Engineering,2017,46(1):135-142.
[20] 陈亮,肖代红,耿正伟,等.固溶温度对挤压态Mg-13Al-6Zn-4Cu合金组织与性能的影响[J].粉末冶金材料科学与工程,2016,21(3):463-469.CHEN Liang,XIAO Dai-hong,GENG Zheng-wei,et al.Effects of solid-solution temperature on microstructure and properties of as-extruded Mg-13Al-6Zn-4Cu alloy[J].Materials Science and Engineering of Powder Metallurgy,2016,21(3):463-469.
[21] 马颖,董海荣,张玉福,等.部分固溶处理对AZ91D镁合金微观组织及力学性能的影响[J].兰州理工大学学报,2015,41(6):1-5.MA Ying,DONG Hai-rong,ZHANG Yu-fu,et al.Effect of partial solid-solution treatment on microstructure and mechanical properties of AZ91D magnesium alloy[J].Journal of Lanzhou University of Technology,2015,41(6):1-5.
[22] 黄正华,郭学锋,张忠明.快速凝固AZ91D镁合金组织的研究[J].材料热处理学报,2005,26(1):32-36.HUANG Zheng-hua,GUO Xue-feng,ZHANG Zhong-ming.Study on microstructures of rapidly solidified AZ91D magnesium alloy[J].Transactions of Materials and Heat Treatment,2005,26(1):32-36.