RE对Al-Si-Cu压铸铝合金组织与性能的影响
发布时间：2018-11-02 15:38
【摘要】：Al-Si-Cu合金具有良好的流动性能、密度低、热稳定性好、耐磨等优点,常作为铸造铝合金广泛应用于汽车、轮船、军工等领域。但是铸造铝合金普遍韧性较差,为进一步提高合金韧性,本文以ADC12压铸铝合金为研究对象,分别单独添加0-2%的稀土 Y、Ce和Nd,对ADC12合金进行变质细化及进行后续的热处理;降低Cu和Fe含量、略微提高Mn和 Mg 含量,制备 Al-xSi-0.55Cu-0.85 Y-0.45Mn-0.45Mg-0.35Fe(x=7.5, 8.5, 9.5 wt%)合金。采用ICP、XRD、OM和SEM进行相组成和组织分析,万能材料拉伸试验机、螺旋流动模具和冲击试验机对比合金的室/高温拉伸力学性能、流动性能和冲击韧性,从而确定最佳的合金化元素类型、含量和热处理工艺参数,建立合金成分与组织、性能之间的内在关系,为高韧性压铸铝合金的开发提供理论依据。主要结果如下:(1) ADC12-xRE 合金由 α-Al、共晶 Si、Al_2Cu、Al_8SiFe2相及 Al-RE 相组成。Y、Ce和Nd三种稀土元素对ADC12合金具有一定的变质效果,变质效果为Y最佳,Ce次之,Nd最差。当Y为0.85 %时,ADC12合金变质效果最佳,合金铸态组织细化最显著。不仅使初生α-Al由粗大树枝晶转变为细小胞状晶和等轴晶,而且使针状共晶Si转变为细小纤维状或颗粒状,分布更均匀,等轴晶和颗粒状的共晶Si硅数目大大增加,同时生成Al3Y新相;此时合金的铸态流动长度、室温抗拉强度、伸长率和冲击韧性分别为1541mm,225 MPa,3.5%和10.8J/cm2,而铸态ADC2合金流动长度、室温抗拉强度、长率和冲击韧性分别为 1287 mm,188 MPa, 1.5 %和 3.8 J/cm2。(2)经过520℃保温8 h热处理后,ADC12合金的组织被细化,抗拉强度为205 MPa,伸长率为1.5%,冲击韧性为7.4 J/cm2;而ADC12-0.85Y合金组织中共晶硅相颗粒发生长大,抗拉强度降低,伸长率提高,冲击韧性大幅提高,与铸态ADC12-0.85Y合金相比,材料韧性显著提高。(3) Al-8.5Si-0.55Cu-0.85Y-0.45Mn-0.45Mg-0.35Fe 合金组织均匀,部分 Al 基体由枝晶状转变为等轴晶,短棒状共晶Si增加。合金具有优异的流动性能,但抗拉强度和伸长率分别为189 MPa和2.0 %,其综合力学性能不及ADC12-0.85Y合金。
[Abstract]:Al-Si-Cu alloy has many advantages such as good fluidity, low density, good thermal stability, wear resistance and so on. It is widely used as casting aluminum alloy in automobile, ship, military industry and so on. But the general toughness of cast aluminum alloy is poor. In order to further improve the toughness of cast aluminum alloy, this paper takes ADC12 die casting aluminum alloy as the research object, separately adding 0-2% rare earth YCe and Nd, respectively. The ADC12 alloy was modified and refined and followed by heat treatment. The content of Cu and Fe was decreased, the content of Mn and Mg was increased slightly, and Al-xSi-0.55Cu-0.85 Y-0.45Mn-0.45Mg-0.35Fe (x _ 2O _ 7.5, 8.5, 9.5 wt%) alloys were prepared. The phase composition and microstructure of the alloy were analyzed by ICP,XRD,OM and SEM. The tensile mechanical properties, fluidity and impact toughness of the alloy at room / high temperature were compared between the universal material tensile tester, the spiral flow mould and the impact tester. Thus the optimum alloying element type, content and heat treatment process parameters are determined, and the internal relationship between alloy composition, microstructure and properties is established, which provides a theoretical basis for the development of high toughness die casting aluminum alloy. The main results are as follows: (1) the ADC12-xRE alloy is composed of 伪-Al, eutectic Si,Al_2Cu,Al_8SiFe2 phase and Al-RE phase. YCe and Nd have a certain modification effect on ADC12 alloy, and the modification effect is the best. Ce was second, Nd was the worst. When Y is 0.85%, the modification effect of ADC12 alloy is the best, and the microstructure refinement of the alloy is the most obvious. Not only the primary 伪-Al is changed from coarse dendrite to fine cellular crystal and equiaxed crystal, but also acicular eutectic Si is transformed into fine fibrous or granular, the distribution is more uniform, and the number of equiaxed and granular eutectic Si silicon is greatly increased. At the same time, the new phase of Al3Y was formed. The flow length, tensile strength, elongation and impact toughness of the as-cast ADC2 alloy were 1 541 mm / 225 MPa,3.5% and 10.8 J / cm 2, respectively, while the flow length, room temperature tensile strength, length ratio and impact toughness of the as-cast ADC2 alloy were 1287 mm, respectively. After heat treatment at 520 鈩，
本文编号：2306211
[Abstract]:Al-Si-Cu alloy has many advantages such as good fluidity, low density, good thermal stability, wear resistance and so on. It is widely used as casting aluminum alloy in automobile, ship, military industry and so on. But the general toughness of cast aluminum alloy is poor. In order to further improve the toughness of cast aluminum alloy, this paper takes ADC12 die casting aluminum alloy as the research object, separately adding 0-2% rare earth YCe and Nd, respectively. The ADC12 alloy was modified and refined and followed by heat treatment. The content of Cu and Fe was decreased, the content of Mn and Mg was increased slightly, and Al-xSi-0.55Cu-0.85 Y-0.45Mn-0.45Mg-0.35Fe (x _ 2O _ 7.5, 8.5, 9.5 wt%) alloys were prepared. The phase composition and microstructure of the alloy were analyzed by ICP,XRD,OM and SEM. The tensile mechanical properties, fluidity and impact toughness of the alloy at room / high temperature were compared between the universal material tensile tester, the spiral flow mould and the impact tester. Thus the optimum alloying element type, content and heat treatment process parameters are determined, and the internal relationship between alloy composition, microstructure and properties is established, which provides a theoretical basis for the development of high toughness die casting aluminum alloy. The main results are as follows: (1) the ADC12-xRE alloy is composed of 伪-Al, eutectic Si,Al_2Cu,Al_8SiFe2 phase and Al-RE phase. YCe and Nd have a certain modification effect on ADC12 alloy, and the modification effect is the best. Ce was second, Nd was the worst. When Y is 0.85%, the modification effect of ADC12 alloy is the best, and the microstructure refinement of the alloy is the most obvious. Not only the primary 伪-Al is changed from coarse dendrite to fine cellular crystal and equiaxed crystal, but also acicular eutectic Si is transformed into fine fibrous or granular, the distribution is more uniform, and the number of equiaxed and granular eutectic Si silicon is greatly increased. At the same time, the new phase of Al3Y was formed. The flow length, tensile strength, elongation and impact toughness of the as-cast ADC2 alloy were 1 541 mm / 225 MPa,3.5% and 10.8 J / cm 2, respectively, while the flow length, room temperature tensile strength, length ratio and impact toughness of the as-cast ADC2 alloy were 1287 mm, respectively. After heat treatment at 520 鈩，
本文编号：2306211
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