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The corrosion resistance of 5083 aluminum alloy after refining with nano-CeB 6 /Al inoculant was investigated by 3.5 wt% NaCl solution, compared with that of as-cast alloy and cold-rolled alloy. It was found that nano-CeB 6 /Al inoculant showed significant grain-refining effect on 5083 alloy and the corrosion resistance of 5083 Al alloy was improved as well. The results of potentiodynamic polarization tests showed that the polarization resistance of refined alloy was higher than that of as-cast alloy and cold-rolled alloy, together with more positive breakdown potential value. The corrosion rate was dependent on the grain size following a power law type relationship, which was attributed to the reduced precipitate on the grain boundary. Unlabelled Image • CeB 6 inoculant can effectively refine 5083 aluminum alloy and improve its corrosion resistance. • The corrosion rate was dependent on the grain size following a power law type relationship. • Refined intergranular precipitates reduce the pitting tendency of aluminum. [ABSTRACT FROM AUTHOR]

The fabrication of AlN/Al composites through nitrogen-bearing gas (NH3) bubbling method into Al melts or Al–Mg melts was once experimentally and analytically studied. The experimental results show that Mg addition greatly enhanced the nitridation rate and volume fraction of AlN. However, a detailed characterization of these changes is still incomplete. This paper presents results of an extensive experimental study and theoretical analysis carried out to investigate the profound effect of the formation of AlN with Mg addition. X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy were used to characterize the microstructure. The edge-to-edge matching crystallographic model which applied to the three common crystal structures (body-centered cubic, face-centered cubic, and hexagonal close packed) was used to analyze and investigate this notable phenomenon. The calculation and analysis of theoretical model manifested that AlN is formed by the direct interfacing of pure Al or Al–Mg and NH3 with active nitrogen, instead of forming into the precursor Mg3N2 first and then the precursor transformed to AlN. [ABSTRACT FROM AUTHOR]

The mechanical properties of iron-rich Al–Si alloy is limited by the existence of plenty of the iron-rich phase (β-Al5FeSi), whose unfavorable morphology not only splits the matrix but also causes both stress concentration and interface mismatch with the Al matrix. The effect of the cooling rate on the tensile properties of Fe-rich Al–Si alloy was studied by the melt spinning method at different rotating speeds. At the traditional casting cooling rate of ~10 K/s, the size of the needle-like β-Al5FeSi phase is about 80 μm. In contrast, the size of the β-Al5FeSi phase is reduced to 500 nm and the morphology changes to a granular morphology with the high cooling rate of ~104 K/s. With the increase of the cooling rate, the morphology of the β-Al5FeSi phase is optimized, meanwhile the tensile properties of Fe-rich Al–Si alloy are greatly improved. The improved tensile properties of the Fe-rich Al-Si alloy is attributed to the combination of Fe-rich reinforced particles and the granular silicon phase provided by the high cooling rate of the melt spinning method. [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]

Sc alloying is usually carried out by adding a small amount of Sc in typical aluminum alloys to improve the mechanical properties, however, the effect of high-Sc content on the microstructure and properties of aluminum alloys is rarely concerned. To further understand the role of Sc alloying, several Al–Sc binary alloys with high-Sc content are designed and the relationship between the Sc content and mechanical properties were investigated. It is found that the mechanical properties of Al–Sc binary alloy is determined by both the Sc content and the cooling rate. The addition amount of Sc shows relatively small effect on the mechanical properties at low cooling rate, but higher at high cooling rate, because cooling rate turns the size and distribution of Al 3 Sc particles. Through the high Sc content alloy design and melt spinning rapid cooling technology, the densely distributed Al 3 Sc precipitate of about 250 nm can be located inside the α-Al grains, resulting in the intracsystalline reinforcement. The combination of high tensile strength (344 MPa) and good plasticity (5.7%) were achieved at a grain size of ~500 nm in the hypereutectic Al–Sc binary alloys ribbons. The significant strengthening could be attributed to multiple strengthening mechanisms including (1) Orowan strengthening; (2) coefficient of thermal expansion (CTE) mismatch strengthening; (3) the Hall-Petch effect caused by grain refinement; (4) solid solution strengthening. When the cooling rate is increased, the effects of thermal mismatch strengthening and Orowan mechanism are more prominent, significantly improving the strength of the Al–Sc alloy. The present experimental results provide an insight into the understanding of microstructural evolution of nanoparticles, and extend the effort for the development of hypereutectic Al–Sc alloys as a member of high-strength structural materials. • Addition of too much Sc fails to enhancement by traditional casting. • Melt spinning causes uniform distribution of Al 3 Sc nanoparticles. • The prepared Al–Sc ribbons exhibit excellent mechanical properties. • Fast cooling and high Sc synergy strengthen Orowan mechanism. [ABSTRACT FROM AUTHOR]

The Al–B–Ca alloy ingot is prepared by arc‐melting with Al–3B and Al–10Ca master alloys and the in situ CaB6–Al4Ca/Al composite inoculant ribbon is carried out through melt‐spinning of Al–B–Ca alloy ingot. Afterwards, Al–B–Ca alloy ingot and CaB6–Al4Ca/Al inoculant ribbon are added into the melt of Al–10Si–0.3Mg alloy as inoculants to verify their refining and modifying effects, respectively. It is found whether in Al–B–Ca alloy ingot or CaB6–Al4Ca/Al inoculant ribbon, CaB6 particles have a cubic shape. Compared to the micron‐sized CaB6 particles in the ingot, the size of CaB6 particles in the ribbon can reach to subnanoscale and nanoscale level. With the same amount of addition, CaB6–Al4Ca/Al inoculant ribbon has a better refining effect than Al–B–Ca alloy ingot, but both of them have similar modifying effects for eutectic silicon. In addition, the mechanical properties of Al–10Si–0.3Mg alloy inoculated by the ribbon are superior to that of Al–10Si–0.3Mg alloy inoculated by the ingot. The mismatch between CaB6 and Al is particularly small and certain orientation relationships are existed between them. Therefore, the impact of CaB6 particle size on refining effect of the inoculants, the heterogeneous nucleation mechanism of CaB6, and the strengthening mechanism of Al–10Si–0.3Mg alloy after inoculation are investigated. The in situ CaB6–Al4Ca/Al inoculant ribbon is prepared through melt‐spinning of Al–B–Ca alloy ingot. CaB6–Al4Ca/Al inoculant ribbon has a better refining effect than Al–B–Ca alloy ingot and the mechanical properties of Al–10Si–0.3Mg alloy inoculated by the ribbon are superior to that of Al–10Si–0.3Mg alloy inoculated by the ingot. Crystallographic orientation relationships are existed between CaB6 and Al. [ABSTRACT FROM AUTHOR]

In this paper, an efficient route that combined addition of excessive Mg (3.6 wt.%) and a trace of La (0.5 wt.%) as well as subsequent T6 heat treatment has been first proposed to modify the detrimental platelet-like β-Al 5 FeSi Fe-rich intermetallic to valuable granular-like π-Al 8 Mg 3 FeSi 6 phase in eutectic Al–Si die alloys. The results of the DSC analysis revealed that majority of Mg play the leading role for precipitation of large script-like π-phase while rare earth La has the significant effect on modifying the eutectic Si phase simultaneously. A new phenomenon has been found that the morphology of the π-phase transformed from the script-like to fine granular-like by two main stages, including fragmentation and growth during solution treatment. By calculation, the coarsening rate coefficient of the segmented π-phase was about 2.9 × 10 − 19 m 3 /h during growth stage. The tensile testing measurements showed that the ultimate tensile strength (UTS), yield strength (YS), elongation to fracture (EI) and the quality index (Q) of T6 treated eutectic Al–Si die alloys alloying with 3.6 wt.% Mg and 0.5 wt.% La can reach 312 MPa, 270 MPa, 4.28% and 406 MPa respectively, and the enhanced mechanical properties corresponding to the evolution of the microstructure. [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]