Characteristics of Ejecta Resulting from Hypervelocity Impact on Al/Mg Explosive Welding Clad Materials

In this study, we propose the use of a clad material, created from aluminum alloy A1100P-H24 and magnesium alloy AZ31B-H24 through explosive welding, as a Whipple shield for space applications. Two kinds clad materials with thickness ratios of Mg: Al = 0.5: 0.5 and Mg: Al = 0.7: 0.3 made from explosive welding, are compared to the current standard, the 1 mm thick A6061-T6 Whipple shield utilized in the international space station. By explosive welding low density, high specific strength, and high impact strength magnesium alloy with aluminum alloy, clad materials achieved 16.8% and 23.7% reduction in area density compared to A6061-T6. In the context of space debris mitigation, we performed hypervelocity impact tests on these clad materials. Detailed comparisons were made between the impact characteristics of the explosive welded clad materials and A6061-T6 by examining the perforation hole size and shape, and by collecting and analyzing the ejecta produced during impact. The experimental results revealed that the clad material with the thickness ratio of Mg: Al = 0.7: 0.3 experienced delamination at the material interface due to the penetration of projectile. On the other hand, the Mg: Al = 0.5: 0.5 clad material exhibited a perforation hole pattern comparable to that of monolithic aluminum and magnesium alloy materials. The cumulative number distribution of ejecta indicated that the clad material with a Mg: Al = 0.5: 0.5 ratio could reduce ejecta production. To further evaluate interface delamination, post-impact ultrasonic analyses were performed on the clad materials.