The statistical analysis of tensile and compression properties of the as-cast AZ91-X%B4C composites

摘要

The statistical distribution of the ultimate tensile strength (UTS) and compression strength (UCS) values of the cast B4C containing Mg matrix composite and its matrix alloy (AZ91) was assessed using different amounts of B4C (1, 3, 5, and 7 wt%) by the use of two-parameter Weibull analysis. Microstructural observations of the composites revealed a reduction in the amount of the Mg17Al12 intermetallic phase, a rather clean interface between B4C particles and the matrix and a good distribution of the B4C reinforcement in the matrix. It was found that the addition of B4C particles to the matrix alloy resulted in the reduction in UTS and elongation values, whereas the compressive strength enhanced slightly. Weibull modulus of the castings was found to be similar to 10 for AZ91 alloy, falling to similar to 6 in the AZ91-7%B4C, but in the compression test, it varied from similar to 52 to similar to 87. The fracture study of the tensile specimens revealed that oxide films and porosity are the main factors for the decreased strength and scattered results, which are increased by using more B4C contents. If the composite can be manufactured with less amount of oxides, it is seen to be more reliable for compressive applications.