Study on microstructure and tensile properties of in situ fiber reinforced aluminum matrix composites

A new in situ fiber reinforced aluminum matrix composites (in situ Al-MMCs) was fabricated based on powder metallurgy (PM). The reinforced fiber was in situ synthesized during hot extrusion procedure of a mixed pure metal powders compact of Al–10 wt%Mg. The microstructure and tensile properties of the in situ Al-MMCs were analyzed and measured. The experimental results showed that the in situ aluminum matrix composites consists of aluminum matrix and fibrous β-Al3Mg2 reinforcement with about tens of microns in diameter and 1 mm in length. Quantitative analysis showed that the content of reinforced fiber is about 18.9 wt%. The tensile stress–strain curve of in situ Al-MMCs involved a remarkable nonlinear deformation region and a long yield plateau region, and the reason is believed to result from deformation induced phase transition of β-Al3Mg2. The yield strength σ0.2, tensile strength and elongation of in situ Al-MMCs is 137 MPa, 147 MPa and 7.0%, respectively. No any fibers pulled out from aluminum matrix can be observed in fracture surface after tensile test. The tensile fracture mechanism of in situ Al-MMCs is quasi-cleavage feature model.