Nano Phase-containing Al-0.3Mn Alloy for Potential EV Applications: Microstructure, Tensile Behavior and Electrical Conductivity

Abstract

- An Al alloy containing 0.3 wt% Mn (Al-0.3Mn) for potential applications in electric vehicles (EV) was prepared by permanent steel mold casting (PSMC) along with high purity (HP) Al (99.9%). The microstructure of the as-cast Al-0.3Mn alloy was analyzed by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The microstructure analyses revealed that the Al-0.3Mn alloy consisted of primary Al phase, micron-sized Al-Fe-Mn intermetallic phase, and nano-sized Al-Mn intermetallic phase. The tensile properties including ultimate tensile strength (UTS), yield strength (YS) and elongation (e f ) were evaluated by tensile testing. The phase sensitive eddy current method was employed to measure the electrical conductivity. The addition of 0.3 wt% Mn increased both the UTS and YS of the cast HP Al significantly to 72.3 and 20.4 MPa from 59.2 and 14.0 MPa. The evaluation of tensile behaviors indicated that the Mn addition significantly improved the resilience and strain hardening rate of the PSMC HP Al, although the toughness of the PSMC Al-0.3Mn was comparable to that of PSMC HP Al. However, the e f and electrical conductivity of the cast alloy decreased to 28.9% and 45.6 %IACS from 37.1% and 61.1 %IACS. The difference in tensile behaviors and electrical conductivities between the PSMC Al-0.3Mn alloy and the PSMC HP Al should be attribute to the emergence of a large amount (2.1%) of the micron Al-Fe-Mn and nano Al-Mn intermetallic phases in the PSMC Al-0.3Mn alloy, compared to only 0.4% of Al-Fe intermetallics in the PSMC HP Al.