Atomic structure and interface chemistry in a high-stiffness and high-strength Al–Si–Mg/TiB2 nanocomposite

Abstract We investigate a new generation of aluminium alloys, Al–Si–Mg/TiB 2 nanocomposites, with both high stiffness (Young's modulus 94 GPa) and high yield strength (322 MPa), designed for automotive applications. A significant lightning (>30%) can be achieved by these nanocomposites compared with conventional Al alloys in components designed for stiffness. The crystallography and distribution of TiB 2 particles and β″ precipitates, as well as the chemistry and structure of Al/TiB 2 interfaces, have been characterized at the atomic scale. The TiB 2 nanoparticles (average particle size ∼450 nm), the main cause of stiffness improvement, were homogeneously distributed within the Al–Si–Mg matrix. The interfaces between Al and TiB 2 nanoparticles were mainly parallel to dense planes of the TiB 2 , including basal { 0001 } , prismatic { 1 1 ¯ 00 } and pyramidal { 01 1 ¯ 1 } planes. All facets show a transitional zone in the alloy matrix, roughly 1 nm in thickness. We also find a Cu-rich layer (∼2 at.%) on pyramidal { 01 1 ¯ 1 } facets. The β″ precipitates are the main cause of high yield strength and work in conjunction with TiB 2 nanoparticles to produce an alloy with outstanding mechanical properties.