Morphological Characterization of a Modified QC-Forming Al Alloy During Tensile Testing
摘要
In this work, the morphology of fractured surfaces and mechanical properties of four icosahedral quasicrystal (IQC) forming alloys from the Al-Mn-Si-Cu-Mg system were evaluated by tensile tests. The synthesized alloys contained varying amounts of TiC, a modifier with inoculant properties that promote heterogeneous nucleation of the primary IQC phase. This allowed us to synthesize alloys with different IQC phase fractions as well as other accompanying intermetallic compounds—mainly the β-AlMnSi phase—and thus obtain a correlation between the different phase fractions and the measured mechanical properties. Our results show that the ultimate tensile strength (UTS) of the gravitationally cast alloys mainly depends on the phase fraction of the hexagonal plate-like β-AlMnSi intermetallic compound, with high β-AlMnSi phase fractions leading to lower UTS and strain values. The fracture surfaces were analyzed by electron scanning microscopy (SEM) to determine possible decohesion between the IQC or other intermetallic phases and the surrounding aluminum matrix, all aiming to obtain a general impression of the morphology of the fracture regarding the matrix, IQC and β-AlMnSi phases. SEM images show an intact interface between both the IQC and β-AlMnSi phases and the surrounding matrix after tensile testing.