Kim Yong-Ho, Yoo Hyo-Sang, Lee Seong-Ho, Lee Gyu-Seok, Son Hyeon-Taek
EV Components & Materials Group, Korea Institute of Industrial Technology, 1110-9 Oryong-dong, Buk-gu, Gwangju 61012, Republic of Korea.
J Nanosci Nanotechnol. 2021 Mar 1;21(3):1984-1989. doi: 10.1166/jnn.2021.18917.
The effect of addition of Mischmetal (MM) on the microstructure, electrical and thermal conductivity, and mechanical properties of the as-extruded Al-MM based alloys were investigated. The studied AlMM alloys (where = 0.2, 0.5, 1.0, 1.5, 2.0 and 5.0 wt.%) were cast and homogenized at 550 °C for 4 h. The cast billets were extruded into 12 mm bars with an extrusion ratio of 39 at 550 °C. The addition of MM resulted in the formation of Al(Ce, La)₃ intermetallic compounds and the area fraction of these intermetallic compounds increased with an increase in the MM content. The Al(Ce, La)₃ phase, which was distributed in the as-cast alloys, was crushed into fine particles and arrayed along the extruded direction during the extrusion process. In particular, these intermetallic compounds in the extruded Al-5.0MM alloy were distributed with a wide-band structure due to the fragmentation of the eutectic phase with a lamellar structure. As the MM content increased from 1.0 wt.% to 5.0 wt.%, the average grain size decreased remarkably from 740 to 73 μm. This was due to formation of Al(Ce, La)₃ particles during the hot extrusion process, which promoted dynamic recrystallization and suppression of grain growth. The electrical and thermal conductivity of the extruded alloys containing up to 2.0 wt.% MM were around 60.5% IACS and 230 W/m · K, respectively. However, the electrical and thermal conductivity of the extruded alloy with 5.0 wt.% MM decreased to 55.4% IACS and 206 W/m · K, respectively. As the MM content increased from 1.0 wt.% to 5.0 wt.%, the ultimate tensile strength (UTS) was improved remarkably from 74 to 119 MPa which was attributed to the grain refinement and formation of Al(Ce, La)₃ intermetallic compounds by the addition of MM.
研究了添加混合稀土（MM）对挤压态Al-MM基合金的微观结构、电导率、热导率及力学性能的影响。所研究的Al-MM合金（其中MM含量分别为0.2、0.5、1.0、1.5、2.0和5.0 wt.%）在550℃下铸造并均匀化4小时。将铸坯在550℃下以39的挤压比挤压成12mm的棒材。添加MM导致形成Al(Ce, La)₃金属间化合物，且这些金属间化合物的面积分数随MM含量的增加而增加。铸态合金中分布的Al(Ce, La)₃相在挤压过程中被破碎成细颗粒并沿挤压方向排列。特别是，挤压态Al-5.0MM合金中的这些金属间化合物由于层片状共晶相的破碎而呈现宽带状结构分布。随着MM含量从1.0 wt.%增加到5.0 wt.%，平均晶粒尺寸从740μm显著减小到73μm。这是由于在热挤压过程中形成了Al(Ce, La)₃颗粒，促进了动态再结晶并抑制了晶粒生长。MM含量高达2.0 wt.%的挤压态合金的电导率和热导率分别约为60.5% IACS和230 W/m·K。然而，MM含量为5.0 wt.%的挤压态合金的电导率和热导率分别降至55.4% IACS和206 W/m·K。随着MM含量从1.0 wt.%增加到5.0 wt.%，极限抗拉强度（UTS）从74 MPa显著提高到119 MPa，这归因于添加MM导致的晶粒细化和Al(Ce, La)₃金属间化合物的形成。
