摘要
以纯铝、Al-20Si和Al-10Sr中间合金为原料,Sr为变质剂(含量为0.01%、0.02%、0.04%和0.06%,质量分数),制备了Al-7Si-xSr、Al-12Si-xSr和Al-20Si-xSr合金,研究了Sr含量对Al-Si合金相变储热材料显微组织及热导率的影响。利用Hot Disk热常数分析仪测量合金的热导率,通过扫描电镜观察及分析合金的显微组织。结果表明:在Al-Si合金中添加变质元素Sr会影响合金的热导率,Al-7Si-0.04Sr合金热导率较Al-7Si合金增加了73.47 W·m^(-1)·K^(-1),Al-20Si-0.04Sr合金的热导率较Al-20Si合金增加了24.09 W·m^(-1)·K^(-1),Al-12Si-0.04Sr合金的热导率较Al-12Si合金增加了17.79 W·m^(-1)·K^(-1)。铝硅合金热导率的增长主要与α(Al)、共晶硅和初晶硅的形貌有关。经过Sr变质之后,Al-7Si合金中共晶Si立体形貌均由片层状转变为珊瑚状,Al-12Si和Al-20Si合金中共晶Si立体形貌由片层状转变为枝条状;其中,Al-7Si合金中α(Al)尺寸明显减少、排列紧密,二次枝晶臂间距逐渐减小;Al-20Si合金中的初晶Si尺寸明显减小,其形貌由多角的大块状变为小块状;α(Al)形态的转变不仅能够为自由电子的传输提供快速通道,而且还会使得共晶Si的排列更加规则,减少自由电子发生散射的几率,对合金的热导率影响较大。共晶Si由片层状转变为珊瑚状或枝条状,增加电子的平均自由程,有利于电子的传输。Al-20Si合金的热导率与初晶Si的形态有着重要联系,大尺寸且形状完整的初晶Si会发生晶格振动,会提高合金的热导率。
Al-7Si-xSr,Al-12Si-xSr and Al-20Si-xSr alloys were prepared using pure aluminum,Al-20Si and Al-10Sr intermediate alloys as raw materials,and Sr as a modifier(content of 0.01%,0.02%,0.04%and 0.06%,mass fraction).The effect of Sr content on microstructure and thermal conductivity of the Al-Si alloy phase change heat storage materials was studied.The thermal conductivity of the alloys was measured by the Hot Disk thermal constant analyzer,and the microstructure of the alloys was observed and analyzed by scanning electron microscopy.The results show that adding the metamorphic element Sr to the Al-Si alloys will affect the thermal conductivity of the alloys.The thermal conductivity of the Al-7Si-0.04Sr alloy is increased by 73.47 W·m^(-1)·K^(-1)compared with the Al-7Si alloy,the thermal conductivity of the Al-20Si-0.04Sr alloy is increased by 24.09 W·m^(-1)·K^(-1)compared with the Al-20Si alloy,and the thermal conductivity of the Al-12Si-0.04Sr alloy is increased by 17.79 W·m^(-1)·K^(-1)compared with the Al-12Si alloy.The increase of thermal conductivity of the Al-Si alloys is mainly related to the morphology ofα(Al),eutectic silicon and primary silicon.After Sr modification,the threedimensional morphology of eutectic Si in the Al-7Si alloy changes from lamellar to coral like,while the three-dimensional morphology of eutectic Si in the Al-12Si and Al-20Si alloys changes from lamellar to dendritic.Among them,the size ofα(Al)in the Al-7Si alloy is significantly reduced,arranged tightly,and the spacing between secondary dendrite arms gradually decreases.The size of primary Si in the Al-20Si alloy significantly decreases,and its morphology changes from multi angular bulk to small pieces.The transformation ofα(Al)morphology not only provides a fast channel for the transmission of free electrons,but also makes the arrangement of eutectic Si more regular,reducing the probability of free electron scattering,and has a significant effect on the thermal conductivity of the alloy.Eutectic Si changes from lamellar to coral or dendritic,which increases the average free path of electrons and is conducive to the transmission of electrons.The thermal conductivity of the Al-20Si alloy is closely related to the morphology of primary Si,the large-sized and fully shaped primary Si will undergo lattice vibration,which will improve the thermal conductivity of the alloy.
作者
张瑞英
李继承
沙君浩
李家康
ZHANG Rui-ying;LI Ji-cheng;SHA Jun-hao;LI Jia-kang(School of Materials Science and Engineering,Inner Mongolia University of Technology,Hohhot 010051,China;Key Laboratory of Light Metals In Mongolia Autonomous Region,Hohhot 010051,China)
出处
《材料热处理学报》
CAS
CSCD
北大核心
2024年第1期53-61,共9页
Transactions of Materials and Heat Treatment
基金
内蒙古自治区科技攻关项目(2021GG0252)
内蒙古工业大学材料科学重点学科团队(ZD202012)。
关键词
AL-SI合金
变质剂Sr
相变储热材料
热导率
Al-Si alloy
metamorphic agent Sr
phase change heat storage material
thermal conductivity
