【摘要】 稀土元素Er能有效细化合金组织，从而影响合金性能，为改善Al-Zn合金力学和热学性能不足，本文研究了Er对Al-Zn合金力学性能和热学性能的影响，制备了Zn含量为10%及Er含量为0, 0.4%, 0.8%和1.2%的Al-10Zn-x Er合金。通过电子探针X射线微区分析仪（EPMA）分析了不同Er含量铸态Al-10Zn-x Er合金的显微组织和元素分布。同时测定了不同Er含量合金的硬度和抗拉强度，并进行了相关性分析。综合评估了合金的固液相变温度、比热容、热扩散系数及导热系数等热学参数。结果表明，Er元素能细化合金的组织，当Er含量为0.4%时，细化效果最明显。同时，过量的Er主要偏析在晶界，Zn主要分布在晶界周围。在Er含量为0.4%时，合金的维氏硬度和抗拉强度达到最大值，分别为HV61.32和135.3 MPa，维氏硬度与抗拉强度的相关系数（r）为0.96，呈显著的线性关系。差示扫描量热分析（DSC）表明，随Er含量增多，合金DSC升温曲线出现小台阶，固液相转变温度先升高后降低，在Er含量为0.4%时达到最高为640.4℃。在100～500℃范围内，Er含量为0.4%合金的比热容、热扩散系数以及导热系数是Al-10Zn-x Er体系最小值。更多还原

【Abstract】 Al-Zn alloy has been widely used because of its advantages of high strength, good casting performance, simple process and low production cost, but it also has some problems such as unstable size and mechanical properties, poor plasticity and low strength at high temperature. Rare earth Er, as a kind of trace element with relatively low price and significant influence on the microstructure properties of alloys, has been widely concerned. It is found that the strengthening effect of Er in aluminum alloy is related to its content. When 0.2%～0.4% Er is added to aluminum alloy, some of Er will form（α（Al）+Al₃ Er） intermetallic compounds in grain boundary segregation except for a small amount of Er dissolved in the matrix, and the rest will form fine primary Al₃ Er phase dispersed in the matrix. The grain refinement of the alloy is obvious, and the high temperature plasticity, thermal stability and strength of the alloy are improved. However, there are few reports on the effects of Er content on the mechanical and thermal properties of Al-Zn alloy, and the change law of the microstructure of Al-Zn alloy with the increase of Er content and the Er content corresponding to the optimal performance have not been clearly obtained. It is of great significance to analyze the microstructure, mechanical and thermal properties of Al-Zn alloys with different Er contents. The microstructure and element distribution of Al-10 Zn-x Er alloys with different Er contents were analyzed by electron probe X-ray microanalysis（EPMA） and energy dispersive spectrometer（EDS）. The micro-Vickers hardness of the alloy was determined, the density of the alloy was measured by the drainage method, the specific heat capacity of Al-10 Zn-x Er alloys at different temperatures was analyzed by differential scanning calorimetry（DSC）, and the phase transition temperature of the alloy was analyzed. The thermal diffusion coefficient of the alloy at different temperatures was determined by laser flash apparatus（LFA）, and the thermal conductivity of the alloy was calculated according to the density, specific heat capacity and thermal diffusion coefficient of the alloy. The results showed that Er could refine the microstructure of Al-10 Zn alloy, and the grain refining effect was most obvious when Er content was 0.4%. With the further increase of Er content, the second phase accumulated in large quantities at the grain boundaries. Zn existed mainly in the form of Al-Zn solid solution, and Er existed in the form of intermetallic compound Al₃ Er. Er element could fine the microstructure of the alloy, and the rare earth Er was dispersed in the grain boundary, which effectively hindered the deformation of the matrix and the movement of the grain boundary, thus improving the hardness and tensile strength of the alloy. When Er content was 0.4%, the refining effect was obvious, Vickers hardness and tensile strength of the alloy reached the maximum value, which were HV 61.32 and 135.3 MPa, respectively. The correlation coefficient（r） between Vickers hardness and tensile strength was 0.96, showing a significant linear relationship. DSC analysis showed that with the increase of Er content, DSC temperature curve of the alloy appeared a small step, the solid-liquid phase transition temperature increased first and then decreased, and reached the highest of 640.4 ℃ when the content was 0.4%. In the range of 100～500 ℃, the specific heat capacity and thermal diffusion coefficient of the alloy with Er content of 0.4% were the minimum values of Al-10 Zn-x Er alloys. With the increase of Er content in Al-10 Zn alloy, Al₃ Er intermediate phase in the alloy increased, and the electron waves were scattered by different phase interfaces, so that the thermal conductivity of the alloy decreased as a whole with the increase of temperature. When Er content was 0.4%, the thermal conductivity of the alloy decreased most significantly with the temperature.更多还原