文档介绍：摘要
过共晶铝硅合金由于具有高强度、低密度、高耐磨性和良好的导热性等优异性能而得到人们的青睐,但是,随着硅含量的增加,合金组织中会生成板片状、针状的共晶硅以及大量粗大且不规则的块状初生硅,严重影响了其加工性能和力学性能。本文通过研究不同体系的变质剂和热处理工艺对过共晶铝硅合金中初生硅和共晶硅的作用,探讨复合变质以及T6热处理对过共晶Al-18Si-2Cu合金组织及性能的影响;并且研究了不同的变质温度下,过共晶铝硅合金组织及性能的变化规律,研究最适合Al-P和Ni基非晶复合变质剂的变质温度。
实验分析发现,Al-P对初生硅有明显的细化变质作用,使过共晶Al-18Si-2Cu合金中的初生硅的平均尺寸由未变质时的130um降低到20um;非晶能增加共晶硅的形核数量,使针状和板片状的共晶硅得到细化,其中,Ni非晶的变质效果比Fe非晶好;T6热处理能使初生硅圆钝化,并且使针状和板片状的共晶硅粒化,从而使Al-18Si-2Cu合金的抗拉强度和延伸率都有一定的提高;通过控制变量法,经对比分析,最适合Ni非晶的变质温度为820℃。
关键词: 铝硅合金初生硅非晶复合变质 T6热处理
Abstract
People think highly of hypereutectic Al-Si alloy,because it has the property of high strength, low density, high abrasion resistance and good thermal conductivity,etc. However, with the increase of the content of silicon, it will result in plate-like and needle-like eutectic silicon, and a lot of rough and irregular block primary silicon in the alloy structure, which would seriously affect the processing performance and mechanical performance of the alloy. Through researching how different kind of modifier and heat treatment affect the primary silicon and eutectic silicon in the hypereutectic Al-Si alloy, to explore the effect of T6 heat treatment posite modification on microstructure and properties of Al-18Si-2Cu alloy. Besides, studied the effect of different modifying temperature on microstructure and properties of Al-18Si-2Cu alloy, seeking the most suitable modifying temperature for Al-P and Ni based amorphous posite modifier.
Experimental shows that, Al-P has obvious effect on grain refinement of primary silicon, after modificated, the average size of primary silicon in eutectic Al-18Si-2Cu alloy reduced from 130um to 30um; the amorphous alloy will increase the number of nucleation of eutectic silicon, which will refine the plate-like and needle-like eutectic silicon, thereinto, the modification effect of Ni based amorphous alloy is betteer than Fe based amorphous alloy; T6 heat treatment can make the primary silicon passivation, and make the of needle and plate sh