PbTe/FeMn热电接头的界面性能及热稳定性研究

Study on the interface properties and thermal stability ofPbTe/FeMn thermoelectric joint

因热膨胀系数失配和机械咬合的界面连接方式,Fe/PbTe热电接头在服役中的力学性能和热稳定性较差。考虑到合金具有热膨胀系数可调性,在纯Fe中添加特定的活性元素,通过扩散和反应在界面处形成冶金结合,可提高界面连接性能。通过高通量实验快速筛选出合金电极Fe_(100-x)Mn_(x)(x=0,5,10,15),利用放电等离子烧结(SPS)技术与n型Pb_(0.98)Ga_(0.02)Te热电材料连接。研究结果表明,FeMn合金电极的热膨胀系数随着Mn含量的升高与Pb_(0.98)Ga_(0.02)Te更加接近,有效降低了界面失配。时效15 d后界面出现Fe-Pb-Ga元素互扩散区,呈现冶金结合特征。其中Fe_(90)Mn_(10)/Pb_(0.98)Ga_(0.02)Te/Fe_(90)Mn_(10)时效15 d后的接触电阻率为10.12μΩ·cm^(2),转换效率稳定在4.3%左右,剪切强度增加至21.44 MPa。上述基于高通量法筛选合金电极的技术路线也为热电界面的设计提供了新的思路。

The mechanical properties and thermal stability of Fe/PbTe thermoelectric joints are poor due to the mismatch of thermal expansion coefficient and mechanical interlocking interface connection.Considering the controllability of the thermal expansion coefficient of the alloy,specific active elements are added to Fe to form metallurgical bonding at the interface through diffusion and reaction,which can improve the interface bonding performance.In this paper,we selected Fe_(100x)Mn_(x)(x=0,5,10,15)alloy as electrodes through high-throughput experiments and connected them with n-type Pb_(0.98)Ga_(0.02)Te using spark plasma sintering(SPS)technology.The results show that the thermal expansion coefficient of FeMn alloy becomes closer to that of Pb_(0.98)Ga_(0.02)Te with the increase of Mn content,which effectively reduces the interface mismatch.The Fe-Pb-Ga element interdiffusion layer appeared at the interface after aging 15 d,which demonstrating metallurgical bonding characteristics.The contact resistivity of Fe 90 Mn 10/Pb_(0.98)Ga_(0.02)Te/Fe 90 Mn 10 is 10.12μΩ·cm^(2)after aging for 15 d.The conversion efficiency remains stable at about 4.3%.The shear strength increases to 21.44 MPa.Based on the high-throughput selection of alloy electrodes,the above technical route provides a new way to design the thermoelectric interface.