Experimental and simulation investigations of tensile response of (Al 2O 3f/Al) w/2024Al composite

Abstract

Tensile response of a 2024Al alloy reinforced with Al 2O 3f/Al composite wires [(Al 2O 3f/Al) w/2024Al composite] has been investigated by both performing tensile tests and using the finite element method (FEM). Microstructure and tensile fracture surfaces of (Al 2O 3f/Al) w/2024Al composites were examined using optical microscope (OM) and scanning electron microscope (SEM), respectively. It is found that the longitudinal tensile response of (Al 2O 3f/Al) w/2024Al composite is nearly elastic up to failure. The longitudinal tensile strength of (Al 2O 3f/Al) w/2024Al composite reaches its fiber bundle strength and the longitudinal elastic modulus is consistent with that predicted using the rule of mixture. The contribution of matrix is negligible to the longitudinal tensile strength but not to the modulus of elasticity. Coating composite wires (CWs) with Ni can improve the interfacial bonding between the CWs and 2024Al alloy. Diffusion annealing can further improve the interfacial bonding. The transverse tensile strength is dependent strongly on the interfacial bonding between the CWs and 2024Al alloy. The stronger the interfacial bonding, the higher the transverse tensile strength. Following the diffusion annealing, ageing treatment can improve the transverse tensile strength of (Al 2O 3f/Al) w/2024Al composite to a higher level due to the increased strength of matrix 2024Al alloy. To reveal the fracture mode of (Al 2O 3f/Al) w/2024Al composite under transverse loading, the transverse tensile response of a model material, (Al 2O 3f/matrix1) w/matrix2 composite, whose microstructure is similar to that of the (Al 2O 3f/Al) w/2024Al composite, was analyzed using FEM. FEM results indicate that, under transverse loading, the stress distribution in the (Al 2O 3f/matrix1) w/matrix2 composite depends on the strength of matrix2. When matrix1 and matrix2 are both pure Al, failure initiates in matrix1. When matrix1 is pure Al and matrix2 is aged 2024Al alloy, however, failure initiates in matrix2 (2024Al). Therefore, for (Al 2O 3f/Al) w/2024Al composites with weak interfacial bonding between CWs and 2024Al matrix, cracks initiate at interfaces between the CWs and 2024Al matrix and propagate along the interfaces and then through 2024Al matrix, resulting in the global fracture. For (Al 2O 3f/Al) w/2024Al composite with strong interfacial bonding between CWs and 2024Al matrix, cracks initiate in either pure Al or 2024Al alloy and then propagate in both Al and 2024Al, resulting in the global fracture.