The Role of Second Phase Intermetallic Particles on the Spall Failure of 5083 Aluminum

5083 aluminum alloy is a light-weight and strain-hardened material used in high strain-rate applications such as those experienced under shock loading. Symmetric real-time (in situ) and end-state (ex situ recovery) plate impact shock experiments were conducted to study the spall response and the effects of microstructure on the spall properties of both 5083-H321 and 5083-ECAE + 30 % cold-rolled (CR) aluminum alloys shock loaded to approximately 1.46 GPa (~0.2 km/s) and 2.96 GPa (~0.4 km/s). The results show that mechanically processing the 5083-H321 aluminum by Equal Channel Angular Extrusion (ECAE), followed by subsequent CR significantly increases the Hugoniot Elastic Limit (HEL) by 78 %. However, this significant increase in HEL was at the expense of spall strength. The spall strength of the 5083-ECAE + 30 % CR aluminum dropped by 37 and 23 % when compared to their 5083-H321 aluminum counterpart at shock stresses of approximately 1.46 and 2.96 GPa respectively. This reduction in spall strength is attributed to the cracking and re-alignment of the manganese (Mn)–iron (Fe) rich second phase intermetallic particles during mechanical processing (i.e., ECAE and subsequent CR), which are consequently favorable to spallation.