Nickel-aluminide cladding on a steel substrate using dual wire arc additive manufacturing

In this study the nickel-aluminide intermetallic cladded on AISI 1010 steed using dual wire arc process. The nickel-aluminide is fabricated in situ through an arc provided by a gas tungsten arc welding process and changing aluminum wire feeding rate. The research findings reveal that at a constant Ni wire feeding rate of 450 mm/min, by decreasing the Al wire feeding rate lower than 800 mm/min, the instability of the melt pool prevents the formation of a uniform deposit on the substrate. Although deposition has been done at an Al wire feeding rate higher than 1600 mm/min, transverse cracks have formed in the clad layer. Increasing the aluminum wire feeding rate from 1000 to 1400 mm/min decreases the dendritic arm size from 9.2 ± 0.1 to 4.1 ± 0.3 μm. Although unreacted nickel is visible in the microstructure at the Al wire feeding rate of 1000 mm/min, at a high feeding rate (1400 mm/min), most of the microstructure contains AlNi and Ni3Al intermetallic compounds. With the rise in Al wire feeding rate from 1000 to 1400 mm/min, both yield strength and ultimate tensile strength increase from 521.45 ± 14.16 to 620.89 ± 16.08 MPa and from 762.11 ± 19.89 to 855.65 ± 21.54 MPa, respectively. Intriguingly, the clad layer's tensile toughness decreases from 26.51 ± 2.43 to 18.32 ± 2.56 MJ m−3. By increasing the wire feeding rate from 1000 to 1400 mm/min, the wear rate at room temperature, 500 °C, and 800 °C increases by 61.2, 45.7, and 44.3%, respectively

Characterization of friction stir welded Al-4Cu-Mg alloy / Al-16Si-4Cu-10SiC composite joint

This study investigated the tool's rotational speed effect during dissimilar friction stir welding of A390–10 wt.% SiC composite-AA2024 aluminum alloy on microstructure, mechanical properties, and corrosion resistance. The results show that the tunnel defect is created on the advancing side at low rotational speeds of 400 and 600 rpm due to insufficient material flow and a high rotational speed of 1200 rpm due to turbulent material flow in the stir zone. Finely equiaxed recrystallized grains are formed in the stir zone under a high plastic strain rate and particle-stimulated nucleation mechanism. The minimum hardness occurs in the TMAZ of the AA2024 aluminum alloy side, and by increasing the rotational speed from 800 to 1000 rpm, the average hardness in the stir zone decreases from 146.06±8.67 to 137.86±3.98 HV0.1. Also, by increasing the rotational speed from 800 to 1000 rpm, the stir zone's yield strength and ultimate tensile strength decrease by 4.9 and 5.2%, respectively. With the increased rotational speed from 800 to 1000 rpm, corrosion current increases from 0.0213 to 0.0225 mA.cm−2, and corrosion resistance decreases by 17 %. After friction stir welding with a rotational speed of 800 rpm and traverse speed of 20 mm/min, the corrosion resistance of the joint increases and decreases compared to the composite base metal and AA2024 aluminum alloy base metal, respectively

Electrochemical aspects and in vitro biocompatibility of Ti-SS304 layered composite

In the current research, in order to eliminate the release of toxic ions from the stainless steel 304 layer, a bi-layered Ti-SS304 biocomposite was made using the friction stir welding process, and the corrosion-cellular behavior of this biocomposite in simulated body fluid (SBF) was studied. The results show that the increasing temperature induced by increasing welding heat input during friction stir welding increases the thickness of the oxide layer formed on the titanium layer. By increasing the thickness of the oxide layer, the corrosion current density increases to 3.45 μA cm−2, the corrosion potential decreases to −0.24 V, and the corrosion rate increases to 0.029 mm/year. In addition, compared to samples fabricated with different traverse speeds of 5, 10, and 20 mm/min, the composite samples fabricated with different rotational speeds of 600, 800, and 1000 rpm did not show significant differences in corrosion current density due to competition effect of the titanium oxide layer and residual stress formed during friction stir welding by different rotational speeds. The two-layered Ti-SS304 composite fabricated at a rotation speed of 1000 rpm and a traverse speed of 20 mm/min shows the lowest corrosion current density and corrosion rate and the highest cell viability of 4.9 × 10 −7 A/cm−2, 4.26 × 10 −3 mm/year, and 92%, respectively

Effect of solution treatment of AZ91 alloy on microstructure, mechanical properties and corrosion behavior of friction stir back extruded AZ91/bioactive glass composite

In the present study, we investigated the effects of solution treatment and friction stir back extrusion on the microstructure, mechanical properties, and in-vitro corrosion behavior of the AZ91/64SiO2–31CaO–5P2O5 composite. The findings demonstrate that the reinforcing phase of bioactive glass in the AZ91 matrix exhibits a gradient distribution, resulting in grain refinement in the zone near the surface of the composite wire. The fabrication of the AZ91-3 vol% bioactive glass composite through friction stir back extrusion, utilizing a rotational speed of 1200 rpm and an extrusion speed of 20 mm/min, leads to a significant improvement in corrosion resistance compared to the solid solutionized AZ91 alloy, as demonstrated by a ∼93% increase in simulated body fluid (SBF). During the friction stir back extrusion of the solid solutionized AZ91 alloy, heat and plastic deformation result in the re-precipitation of the ß-Mg17Al12 phase in the α-Mg matrix. The presence of bioactive glass particles facilitates this re-precipitation process during friction stir back extrusion. In comparison to the solid solutionized AZ91 alloy, the AZ91-3 vol% bioactive glass composite exhibits a 23% increase in ultimate tensile strength (UTS), a 28% increase in yield strength (YS), and a 30% decrease in elongation

Effect of preprocessing heat treatment of the Al-16Si-4Cu alloy on microstructure and tribological behavior of friction-surfaced coating

This study investigated the simultaneous effect of the consumable rod's preprocessing heat treatment conditions (homogenization, solid solution, and artificial aging treatment) and severe plastic deformation on the properties of Al-Si-Cu alloy friction surfaced on a commercially pure aluminum alloy substrate. The friction-surfaced coating's microstructural evolution, mechanical properties, and wear resistance were evaluated. The results showed that coatings fabricated using artificially aging (T6)-treated consumable rods resulted in the highest coating width (17.02±0.83 mm) and maximum efficiency (39.78 ± 1.23 %). Friction surfacing using artificially aged and solid solution-treated consumable rods results in minimum (2.78 ± 0.28 µm) and maximum (6.32±0.34 µm) coating grain sizes, respectively. Friction surfacing using T6-treated consumable rods results in smaller, more uniformly distributed Si particles in the coating microstructure. Compared to the other consumable rods, the coatings fabricated using T6-treated consumable rods result in the highest hardness (110.54±10.29 HV0.1), maximum bond strength (14.15±0.75 kN), and lowest wear rate (0.20±0.03 µg/Nm)