Atomic-scale investigation of the interface precipitation in a TiB2 nanoparticles reinforced Al–Zn–Mg–Cu matrix composite

Abstract

The effects of nanosized reinforcement particles on precipitation reactions in age-hardenable Al alloy matrix composites have been largely unknown. In this work, an Al-Zn-Mg-Cu matrix composite reinforced with uniformly distributed TiB2 nanoparticles was successfully produced.The solid-soluted, peak-aged and overaged materials were then characterized, at the atomic scale using (high-resolution) scanning transmission electron microscopy, to provide a fundamental insight into the interface precipitation. Our results demonstrated that the facetted TiB2 nanoparticles have a significant impact on the precipitation in matrix areas adjacent to the TiB2/Al interfaces. The interfaces after solid-solution treatment are tightly-bonded and oxide-free, and display two orientation relationships (ORs): the well-reported [2 1 � 1 � 0]TiB 2 //[101]Al, (0001)TiB 2 //(1 � 11)Al (OR1) and the new [21 � 1 � 0]TiB 2 //[101]Al, (011 � 0)TiB 2 //(111 � )Al (OR2). The interface 2precipitates (i.e. interphase) having the size of several tens of nanometers were formed after ageing and were determined to be (Zn1.5Cu0.5)Mg phase. Their formations were only related to the initial OR1 and OR2 where the mutual ORs between the TiB2, interphase and Al matrix were further developed. Periodically spaced misfit dislocations were revealed at the semi-coherent TiB2/Al interfaces, which are generally considered beneficial to the heterogeneous precipitation. They not only reduced nucleation energy barrier, but also acted as short-circuit diffusion paths for transporting solute atoms and vacancies, accelerating growth rate. However, the growth of interphase at the interface parallel to close-packed {111} Al planes was suppressed by the ultralow accommodation factor. In addition, such an interface precipitation reduced the mismatch of the TiB2/Al interface, increasing the overall coherency and being potential for effective interface strengthening.

Achieving simultaneously improved tensile strength and ductility of a nano-TiB2/AlSi10Mg composite produced by cold spray additive manufacturing

“…8c 9b and c). This OR is consistent with previous literature [33,34]. The overall semi-coherent TiB2/Al interface due to the in-situ chemical reaction in the melt contributed to the formation of the high interfacial bonding [34].…”

“…This OR is consistent with previous literature [33,34]. The overall semi-coherent TiB2/Al interface due to the in-situ chemical reaction in the melt contributed to the formation of the high interfacial bonding [34]. The microhardness of the composite deposits in the stir zone is about 110±3 HV0.1, which is much higher than that of the pure AlSi10Mg sample (82 HV0.1) due to the reinforcement of nano/micro TiB2 particles.…”

Fabrication of fine grain structures in Al matrices at elevated temperature by the stimulation of dual-size particles

“…1(d)) and nano-scaled particles (20-500 nm, Fig. 1(e)), and the majority of nano-TiB 2 particles display well coherent orientations with Al matrices, as characterized in our former studies [33,34]. Initially, large amounts of in-situ TiB 2 particles are clustered on the casting grain boundaries, as shown in Fig.…”

Simultaneously minimizing residual stress and enhancing strength of selective laser melted nano-TiB2 decorated Al alloy via post-uphill quenching and ageing

“…In the present study, we used a home-made in-situ nano-TiB 2 decorated Al-7Si-Mg (TiB 2 /Al-7Si-Mg) alloy powder, fabricated by the saltmetal reaction and gas atomization, because in-situ TiB 2 particles have various advantages as a reinforcer of Al alloys (details can be found in our previous studies [30][31][32][33]). The alloy powders are spherical in shape and have a particle size in the range of 15-53 μm.…”