Al/Niobium Diboride Nanocomposite’s Effect on the Portevin-Le Chatelier Phenomenon in Al-Mg Alloys

Abstract

In Al-Mg alloys, the Portevin-Le Chatelier phenomenon, or dynamic strain aging, reveals itself as serrations upon plastic tensile deformation. This research evaluates this phenomenon when Al/NbB2 nanocomposite pellets are added to a magnesium-supersaturated Al matrix. A ball-milled 90 wt % Al and 10 wt % NbB2 nanocomposite helped inoculate an Al-Mg melt to incorporate the nanoparticles effectively. The melt was cast into rods that were cold-rolled into 1 mm diameter wires. Two sets were prepared: The first group was an as-cast set of samples, for comparison purposes, whereas the second was a solution-treated set. The solution treatment consisted of annealing followed by ice-water quenching. The results corroborating that the phenomenon was observable only in the specimens bearing the solution treatment, were used as the research baseline. Said treated alloy was compared to one containing the nanoparticles, which proved that the NbB2 particles caused a reduction of the serrated signal amplitude.

Multi-Objective Optimization of Novel Aluminum Welding Fillers Reinforced with Niobium Diboride Nanoparticles

“…Figure 2 shows the filler manufacturing steps, i.e., NbB 2 particle manufacturing, stir casting, and quality testing. Before manufacturing the proposed experimental filler, NbB2 particles must be prepared and embedded into an aluminum matrix through cold welding [6,10,[13][14][15][16]. Stir casting then further improves the bonding of the reinforcing particles due to melt agitation [21].…”

“…The rotational speed was set at 1020 rpm for 1 h, with a BPR of 10:1 [24] (Figure 2c). After cold welding, we sintered the pellets to enhance the aluminum/diboride interface to reduce porosity [6,10,[13][14][15][16]. A 200 °C annealing for 30 min in a reduced vacuum atmosphere (4 kPa) permitted the enhancement of the aluminum/diboride interface by removing residual stresses in the Al/NbB2 composite produced during the intense plastic deformation To ensure proper particle dispersion during pellet fabrication, we used a hot plate stirrer to mix an isopropanol solution with the NbB2 and pure Al powder, with an Al-to-NbB2 mass ratio of 90:10 (Figure 2b).…”

“…Furthermore, incorporating nanoparticles has raised a given metal's mechanical strength [10][11][12]. For instance, the addition of niobium diboride (NbB 2 ) nanoparticles strengthens a pure aluminum matrix used in wire fabrication [6,[13][14][15][16], showing improvements in strength, oxidation resistance, operating temperature, stiffness, wear resistance, and increasing the electrical conductivity [2,6,15,17]. A high strength-to-weight ratio makes these nanocomposite materials apt for structural applications [9,17,18].…”