Search

In situ CeB 6 /Al composite has been proven to be an effective refiner for commercial pure aluminum, however, it remains unclear as to the mechanisms of synthesis and grain refinement. We use low-temperature alloying and high-speed melt spinning to optimize the microstructure of CeB 6 . It is found that in situ CeB 6 /Al composite shows controllable microstructure and its refining effect is obviously dependent on the size of CeB 6 particle/cluster. As nano-CeB 6 particles self-assemble into submicron clusters, the inoculant shows significantly enhanced refining effect, reducing the grain size of pure aluminum to ∼110 μm. The refining mechanism is attributed to the combining effect of the cluster structure in submicron scale and the excellent crystallography matching relationship of CeB 6 and Al. Mechanical properties of pure aluminum are also improved by addition of in situ CeB 6 /Al composite inoculant due to collaboration effect of dispersion strengthening and grain refining strengthening. [ABSTRACT FROM AUTHOR]

Hybrid aluminum matrix composites have received widespread attention because of their superior performance to single-phase reinforced aluminum matrix composites. In situ VB 2 –AlN–Al 4 C 3 –VSi 2 /Al ribbons with polyphasic and multi-scale reinforcement particles were prepared by powder metallurgy method and controlled by melt-spinning and then verified the reinforcement efficacy in Al–12Si alloy. It was found that the addition of VB 2 –AlN–Al 4 C 3 –VSi 2 /Al ribbons not only refined the grain of α-Al, but also optimized the morphology of eutectic silicon for Al–12Si matrix composite. Thereafter, the mechanical properties of the VB 2 –AlN–Al 4 C 3 –VSi 2 /Al–12Si composite, including the tensile strength, ductility and hardness were increased by 36.2%, 82.2% and 33.4%, respectively, with the addition of VB 2 –AlN–Al 4 C 3 –VSi 2 /Al ribbons. The excellent mechanical properties can be attributed to the micron-sized VSi 2 particles, nano-sized AlN, VB 2 , and Al 4 C 3 as well as the well-bonded particle/matrix interface. In addition, multiple strengthening mechanisms have also made outstanding contributions to the improvement of the mechanical properties, including (1) Orowan strengthening; (2) Coefficient of thermal expansion (CTE) mismatch strengthening; (3) the Hall-Petch effect caused by grain refinement. The present experimental results provide an insight into the understanding of polyphasic and multi-scale reinforcement particles, and extend the effort for the development of Al–Si composite. • In situ polyphasic and multi-scale particles was prepared by PM and melt-spinning. • Inoculant ribbons refine the α-Al grain and optimize the morphology of eutectic silicon. • VB 2 –AlN–Al 4 C 3 –VSi 2 /Al interface is clean and well lattice-matched. • The VB 2 –AlN–Al 4 C 3 –VSi 2 /Al–12Si composite exhibit excellent mechanical properties. [ABSTRACT FROM AUTHOR]

• TiN-AlN/Al inoculant was prepared by melt-spinning with Si 3 N 4 as a nitrogen source. • HRTEM shows that an orientation difference of 17° 11′ between (1 1 1) TiN and (1 1 1) Al. • Mechanical properties of pure Al improved by adding AlN-TiN/Al after sonication. A new in-situ TiN-AlN/Al composite inoculant with submicron structure was developed by arc melting and melt spinning method using Si 3 N 4 as nitrogen source. Under ultrasonic condition, the as-spun inoculant ribbon shows significant refining effect for pure Al, leading to an obviously reduced grain size from 780 μm to 140 μm and increased tensile strength from 57 MPa to 140 MPa. It is found that an obvious crystal orientation difference of 17° 11′ is presented between the TiN crystal and the Al matrix, which helps to form a coherent interface. It is proved that TiN can be used as an effective heterogeneous substrate for nucleation of Al crystals. [ABSTRACT FROM AUTHOR]