Effects of AlB2 Particles and Zinc on the Absorbed Impact Energy of Gravity Cast Aluminum Matrix Composites

• Published in: JOM (1989) Vol. 66; no. 6; pp. 926 - 934
• Main Authors: Corchado, Marcos, Reyes, Fernando, Suárez, Oscar Marcelo
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.06.2014
• Subjects: Chemistry/Food Science; Earth Sciences; Engineering; Environment; Physics; Charpy Impact Test; Aluminum Matrix Composite; Brinell Hardness; Absorb Impact Energy; Void Coalescence
• ISSN: 1047-4838; 1543-1851
• DOI: 10.1007/s11837-014-0911-5

The effect of different amounts of boron, in the form of AlB 2 particles, as well as zinc concentration in a gravity cast Al-B-Zn composite, was studied and related to the absorbed energy upon fracture during Charpy impact experiments. In addition, the authors correlated the composite Brinell hardness with the quantitative assessment of brittle and ductile fracture areas of the Charpy fractured specimens and found that increasing AlB 2 particle concentration resulted in a reduction of absorbed impact energy. Although larger zinc levels produced somewhat similar results, the AlB 2 effect was prevalent. The energy absorption upon impact reached a maximum when no particles were present; conversely, the lowest amount of absorbed energy corresponded to a composite with a composition of 15 wt.% Zn and 8% in volume of AlB 2 , i.e., the highest concentration of AlB 2 and zinc studied. Raising the amount of AlB 2 as well as zinc, as expected, resulted in higher Brinell hardness. A statistical analysis allowed studying of the particle size distribution, whereas values for crack tip opening displacement were subsequently calculated for the range of particle sizes found and the corresponding AlB 2 particle volume percent. Higher porosity values were measured for larger AlB 2 volume percent. Finally, analyses of fracture surfaces corroborated that brittle fracture was favored in composites with higher amounts of AlB 2 and zinc.