合金化及变质处理对Al-20Si合金机械性能的影响

发布时间：2018-07-04 07:40

  本文选题：过共晶Al-20Si合金 + 初晶硅　； 参考：《沈阳理工大学》2017年硕士论文

【摘要】：过共晶铝硅合金与普通钢铁材料相比具有密度小、比强度高、热膨胀系数低、耐磨损等优点,被广泛用于航空航天、汽车、高速列车、建筑、电子产品等领域。但是随着硅含量的增加,过共晶铝硅合金中存在的形貌粗大初晶硅,长针状共晶硅,严重的割裂了基体,降低了过共晶铝硅合金的机械性能。因此,开展增强过共晶铝硅合金机械性能研究极具意义。论文研究的主要内容和结论如下:本课题主要研究在过共晶Al-20Si合金中添加金属元素Mg、Ti、Mn、Cu、Ni、Bi,细化变质剂Al-P、稀土元素Ce和La后的过共晶多元Al-20Si合金,通过改变Ni、Bi两种金属元素在合金中的含量,并将合金经过T6热处理,研究合金中组织形貌的变化对合金机械性能的影响。利用AFT-DC130光学显微镜,观察过共晶多元Al-20Si合金的金相组织。实验结果证明Bi元素对经过变质处理后合金中的初晶硅影响不大,但能够使合金中的共晶硅发生球化现象。Ni元素不仅可以使共晶硅细化,还能够与多元合金中的其他金属元素结合形成网状、长条状等不规则形状,经过XRD分析可知为A13Ni、A17Cu4Ni等富Ni相金属化合物。利用HVS-5维氏显微硬度计,测试过共晶多元Al-20Si合金的硬度。结果表明随着Bi含量的增加,合金的硬度呈逐渐减小的趋势;而随着Ni含量的增加,合金的硬度呈现逐渐增加的趋势。利用YDX-Ⅲ9702压电式测力仪测量轴向切深ap分别为0.4～0.8mm,进给量f为100～300mm/min,主轴转速n为470～650r/min条件下合金的切削力。结果证明合金的切削力随着Ni含量的增加呈现先增加后减小得趋势,合金的表面粗糙度则随着Ni含量的增加而降低。通过对Ni含量为0.8%和1.2%的两组实验合金的切削力进行计算,得出合金切削力通用公式中的系数。Ni含量为0.8%和1.2%的两组实验合金切削力通用公式如下:Ni 含量为 0.8%: F=9.8. ..B.Z (单位/N)Ni 含量为 1.2% : F=9.8 . . . B . Z (单位/N)利用MMW— 1A组态控制万能摩擦磨损试验机,在试验力45N,转速300 r/min,持续时间为10 min条件下进行干摩擦磨损实验,然后用BS124S型天平称量合金失重。结果表明,由于Bi元素具有自润滑作用,随着Bi的质量百分数从0.0%增加到1.5%后,合金的摩擦系数从0.74下降到0.58,磨损量从2.8mg减小到2.3mg。随着Ni的百分含量从0.4%增加到1.2%后,合金的硬度增加,合金的摩擦系数从0.74下降到0.52,磨损量从2.8mg减小到2.1mg,磨损机制由黏着磨损转变为轻微的磨粒磨损和疲劳磨损,合金的耐磨性能提高。
[Abstract]:Hypereutectic Al-Si alloy has the advantages of low density, high specific strength, low coefficient of thermal expansion, wear resistance and so on. It is widely used in aerospace, automobile, high-speed train, building, electronic products and other fields. However, with the increase of silicon content, the morphology of primary silicon and long needle eutectic silicon in hypereutectic aluminum-silicon alloy are coarse, which seriously split the matrix and reduce the mechanical properties of hypereutectic Al-Si alloy. Therefore, it is of great significance to study the mechanical properties of hypereutectic Al-Si alloys. The main contents and conclusions of this paper are as follows: in this paper, the hypereutectic multicomponent Al-20Si alloy after the addition of the metal element MgTI-TiMnMn-Cu-NiBi, the refined modifier Al-P, the rare earth element ce and La was studied. The effect of microstructure and morphology on the mechanical properties of the alloy was studied by changing the content of the two kinds of metal elements in the alloy and heat treatment of the alloy with T6. The microstructure of eutectic multicomponent Al-20Si alloy was observed by AFT-DC130 optical microscope. The experimental results show that Bi element has little effect on the primary silicon in the alloy after modification, but it can make the eutectic silicon spheroidized in the alloy. The Ni element can not only refine the eutectic silicon. It can also be combined with other metal elements in the multicomponent alloy to form irregular shape such as network and long strip. By XRD analysis, it can be known as Ni rich metal compounds, such as A13NiGN, A17Cu4Ni and so on. The hardness of hypereutectic multicomponent Al-20Si alloy was measured by HVS-5 Vickers microhardness meter. The results show that the hardness of the alloy decreases with the increase of Bi content and increases with the increase of Ni content. YDX- 鈪，

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