Effect Of Precipitation Hardening Research Articles

Impacts of the alloying elements and thermo-mechanical processing on the phase stability, crystalline structure, microstructure, and selected mechanical properties of Ti-(10-x)Al-xV (x = 0, 2, and 4 wt%) alloys targeted as external prostheses

This study aimed to characterize Ti-Al-V alloys submitted to thermo-mechanical processes and evaluate their impact on the crystalline structure, microstructure, coefficient of thermal expansion (CTE), selected mechanical properties, and cytotoxicity. X-ray diffraction (XRD) analysis revealed a major α phase, with V acting as a β-stabilizer. The cooling rate and the plastic deformation contributed to the formation of minor martensitic α′ and β phases, with notable variations in cell parameters. The Energy-Dispersive XRD indicated the CTE was dependent on the alloying elements. Ti-10Al and Ti-8Al-2V depicted Widmanstätten laths and basket-weave structures, while Ti-6Al-4V showed typical features of β grain boundaries. Thermodynamic predictions aligned with the observed phase compositions. Vickers micro-hardness tests yielded values surpassing those of commercially pure titanium (CP-Ti), attributed to the synergistic effects of solid solution, phase precipitation, and strain hardening effects. And, elastic modulus approximated that of CP-Ti, largely due to the α phase's predominance. The solution treatment reduced the elastic modulus compared to the hot-rolled samples due to the stress relief and α′ and β phase precipitation. Preliminary cytotoxicity assays confirmed the non-toxicity of the samples to cell viability. These findings suggest that the solutionized Ti-10Al sample is an economically viable candidate for fabricating external prostheses.

The impact of heat treatment process on the drilling characteristics of Al–5Si–1Cu–Mg alloy produced by sand casting

Aluminum–Silicon (Al–Si) based materials are commonly preferred in engineering studies requiring high mechanical performance as an alternative to steel materials. These alloys are especially preferred in the automotive industry, aerospace components and heavy machinery parts. In post-casting processes, machining operations are of great importance for high geometric precision, surface quality and longer fatigue life in mechanical environments. In this research, the microstructural, mechanical and machining characteristics of the Al–5Si–1Cu–Mg material produced by sand casting method in both as-cast (AC) and heat-treated (HTed) (Solid solution, quenching and aging-SQA) states were experimentally investigated. Microstructural examinations were carried out with optical microscope and SEM images. Mechanical properties were determined by tensile and hardness tests. Then, drilling experiments were performed in the CNC vertical machining center with 8 mm diameter uncoated HSS (High Speed Steel) cutting tools at constant cutting conditions (i.e., cutting speed-V: 125 m/min, feed rate-f: 0.05 mm/rev and depth of cut-DoC: 15 mm). In microstructural investigations, it was determined that the microstructure of the Al–5Si–1Cu–Mg material in AC state consists of α-Al, eutectic Si, β-Fe (β-Al5FeSi) and π-Fe (π-Al8Mg3FeSi6) intermetallics. After the SQA, the existing phases generally exhibited a spherical structure, and it was seen that the β phase in the microstructure transformed into the Ɵ (Al7FeCu2) phase. SQA improved the hardness, yield and tensile durability of the material, whereas decreasing the elongation to fracture. SQA process improved the machining characteristics of the material by decreasing thrust force, moment, surface roughness and built-up edge (BUE) formation. The machined subsurface structure of HTed alloy under constant cutting conditions was determined to be more stable and smooth and the machined surface microhardness of HTed alloy was higher compared to as-cast alloy due to the effect of solid precipitation hardening. In addition, shorter and more broken chips occurred in the machining of HTed alloys due to the effect of low elongation to fracture.

Enhanced mechanical and damping properties of Cu-Modified Al-Ni eutectic alloys: Solid-solution and precipitation hardening effects

The study aimed to analyze the mechanical properties, precipitation strengthening, and microstructure of Al-Ni-Cu alloys to understand their enhanced characteristics. Additionally, the damping behavior was examined using a dynamic mechanical analyzer across a continuous heating temperature range with frequencies from 0.5 to 15 Hz. The experimental results indicate that the Al-Ni eutectic alloy, which exhibits an ultrafine Al3Ni intermetallic fiber-reinforced Al matrix, transitions to a dendritic-ultrafine eutectic composite structure. The Cu-containing alloys exhibit two distinct primary phases: α-Al and Al-Ni-Cu ternary intermetallic compounds. The eutectic matrix transforms from Al-Al3Ni to Al-Al7Cu4Ni, and subsequently to Al-Al2Cu. These microstructural evolutions result in an enhancement of the tensile yield strength from 170 MPa to 440 MPa, with additional hardening achieved through aging-induced precipitation. Moreover, the damping capacity improves with the addition of Cu at elevated temperatures, and there is an increase in frequency dependence. This paper will discuss the microstructural features, mechanical properties, deformation behaviors, and damping properties in detail.

Impact of in-process cooling and tool rotation speed on the mechanical and microstructural characteristics of friction stir processed AA2024

Despite significant grain size refinement, friction stir processing (FSP) of heat-treatable aluminum alloys is found to degrade the alloys of strength and hardness qualities. The drop in strength brought on by coarsening or the dissolution of the strengthening precipitate(s) could not be made up for by the improvement in strength brought about by the refinement of grain size following FSP. In order to get around this, the current work looks into a practical method of heat rejection from the FSP zone in addition to grain size refinement during FSP of AA2024 to regulate the precipitate evolution. Under natural cooling, air cooling, and CO2 cooling conditions, friction stir processing (FSP) was used to change the microstructure of Solutionized AA2024 at three distinct rotation speeds of 750, 1180, and 1500 rpm (fixed traverse speed of 50 mm/min). The microstructural evolution (through optical microscopy and SEM) and mechanical properties of FSP samples under different conditions of rotation speed and cooling and their differences were mainly discussed. All the FSP samples have a higher Vickers hardness than the base metal (minimum variation of 16.79% and maximum variation of 41.05%). The maximum hardness, yield strength, tensile strength, and elongation have been obtained under air cooling conditions and a rotation speed of 1180 rpm, which is a result of the simultaneous and effective effect of grain boundary strengthening and precipitation hardening.

Mechanical Bonding Properties of Solderable Anisotropic Polymer Composite containing Low-Melting-Point and High-Melting-Point Solder Fillers

In this papers, to enhance the mechanical bonding properties of solderable anisotropic polymer composites (SAPCs) containing low-melting-point solder filler only, a new low-melting-point solder and high-melting-point solder mixed filler filled SAPCs (LH-SAPCs) was proposed, and the influence of the high-melting-point solder filler on the conduction path formation and mechanical bonding properties of the LH-SAPC were investigated. Two types of LH-SAPC were synthesized by adding high-melting-point solder within the low-melting-point solder/high-melting-point solder mixed filler at mixing ratios of 0 and 50 vol% (the volume fraction of low-melting-point solder/high-melting-point solder mixed filler in the polymer composite was 20%), and a bonding test was conducted using QFP. The results exhibited that the LH-SAPC containing high-melting-point solder formed a wide and stable conduction path due to the proper selective conduction path formation behavior by the interaction between molten low-melting-point solder and solid-state high-melting-point solder fillers within the polymer composite with low viscosity condition. Furthermore, the mechanical bonding properties of the LH-SAPC joints containing high-melting-point solder were enhanced compared to that of LH-SAPC containing low-melting-point solder only owing to the precipitation hardening and dispersion strengthening effects due to the increase of fine Bi-rich, Cu<sub>6</sub>Sn<sub>5</sub>, and Ag<sub>3</sub>Sn intermetallic compound particles inside the conduction path.

Combined Effect of Particle Reinforcement and T6 Heat Treatment on the Compressive Deformation Behavior of an A357 Aluminum Alloy at Room Temperature and at 350 °C

Solid state sintering of cast aluminum powders by resistance heating sintering (RHS), also known as spark plasma sintering or field-assisted sintering technique, creates a very fine microstructure in the bulk material. This leads to high performance material properties with an improved strength and ductility compared to conventional production routes of the same alloys. In this study, the mechanical behavior of an RHS-sintered age-hardenable A357 (AlSi7Mg0.6) cast alloy and a SiCp/A357 aluminum matrix composite (AMC) was investigated. Aiming for high strength and good wear behavior in tribological applications, the AMC was reinforced with a high particle content (35 vol.%) of a coarse particle fraction (d50 = 21 µm). Afterwards, separated and combined effects of particle reinforcement and heat treatment were studied under compressive load both at room temperature and at 350 °C. At room temperature compression, the strengthening effect of precipitation hardening was about twice as high as that for the particle reinforcement, despite the high particle content. At elevated temperatures, the compressive deformation behavior was characterized by simultaneously occurring temperature-activated recovery, recrystallisation and precipitation processes. The occurrence and interaction of these processes was significantly affected by the initial material condition. Moreover, a rearrangement of the SiC reinforcement particles was detected after hot deformation. This rearrangement lead to a homogenized dispersion of the reinforcement phase without considerable particle fragmentation, which offers the potential for secondary thermo-mechanical processing of highly reinforced AMCs.

Insights into microstructural stability and embrittlement of TC25 high temperature titanium alloy subjected to thermal exposure

High temperature titanium alloys are being urgently developed owing to the requirements of advanced aerospace industry. Performance of the alloys in service under high-temperature environments always attracts great attention. In this study, variations of microstructure and mechanical property in TC25 (Ti-6.5Al-2Mo-1Zr-1Sn-1 W-0.2Si) dual-phase high temperature titanium alloy subjected to thermal exposure have been systematically investigated by coupling microstructural characterization, compositional analyses and mechanical measurement. It is found that strength is significantly enhanced while ductility is sharply degraded when the alloy is thermally exposed at 550 °C for a long duration of 100 h. Microstructural observations manifest that ternary α-needles (αt) are drastically precipitated from β-ligaments inside transformed β-matrix (βtrans) whilst α2 (Ti3Al)-phase is produced from primary α-phase (αp) through ordered transformation. The precipitation of αt-needles is promoted by β-phase metastability resulting from insufficient element partitioning in the initial microstructure. The β-phase stability also renders αt-precipitation encounter size effect of β-ligaments, where the precipitation is suppressed when β-ligaments are thin in size. Both precipitation of αt-needles and α2-phase triggers precipitation-hardening effect, which results in strain localization and thereby regresses alloy ductility. However, further analysis indicates that compared with α2-phase, αt-precipitation plays more adverse role in embrittlement in the current alloy. This is different from thermal-exposed behavior of most of high temperature titanium alloys reported in literatures. These findings enrich our fundamental understanding on thermal stability of high temperature titanium alloys, and provide plausible implication to improve high temperature performance via controlling phase precipitation.

The Development of a High-Strength Mg-10.3Gd-4.4Y-0.9Zn-0.7Mn Alloy Subjected to Large Differential-Thermal Extrusion and Isothermal Aging.

The large differential-thermal extrusion (LDTE) process, a novel approach for efficiently fabricating a high-strength Mg-10.3Gd-4.4Y-0.9Zn-0.7Mn (wt.%) alloy, is introduced in this work. Unlike typical isothermal extrusion processes, where the ingot and die temperatures are kept the same, LDTE involves significantly higher ingot temperatures (~120 °C) compared to the die temperature. For high-strength Mg-RE alloys, the maximum isothermal extrusion ram speed is normally limited to 1 mm/s. This research uses the LDTE process to significantly increase the ram speed to 2.0 mm/s. The LPTE-processed alloy possesses a phase composition that is similar to that of isothermal extruded alloys, including α-Mg, 14H-type long-period stacking ordered (LPSO) and β-Mg5(Gd, Y) phases. The weakly preferentially oriented α-Mg grains in the LDTE-processed alloy have <101¯0>Mg//ED fibrous and <0001>Mg//ED anomalous textures as their two main constituents. After isothermal aging, high quantitative densities of prismatic β' and basal γ' precipitates are produced, which have the beneficial effect of precipitation hardening. With a yield tensile strength of 344 MPa, an ultimate tensile strength of 488 MPa, and an elongation of 9.7%, the alloy produced by the LDTE process exhibits an exceptional strength-ductility balance, further demonstrating the potential of this method for efficiently producing high-strength Mg alloys.

Making a coherent L12-nano-precipitates-reinforced Ni-based alloy ultrastrong and ductile by constructing dual heterogeneous structures

It is known that inhibiting rapid decline of strain hardening is crucial in enhancing uniform ductility under uniaxial tension stress for metallic materials with high yield stress. In this study, a high-mechanical-response Ni-based alloy was introduced by fabricating a dual-heterogeneous structure allowing to provide improved strain-hardening capability at both ambient and cryogenic temperatures. Especially at cryogenic temperature, an exceptional strength-ductility synergy with yield strength of 1.85 GPa and ductility of 24% can be achieved, accompanied by a distinctive five-stage strain-hardening response. In such a case, deformation twinning behavior was activated successfully to assist the strain hardening in the Ni base alloy although precipitation-hardening effect was available. Our work sheds light on the strain hardening effect assisted by twinning previously unexpected in coherent precipitation-hardened Ni base alloys, and hence represents a promising route for improving uniform ductility of Ni base alloys with high yield strength.

Microstructural characteristics and low-cycle fatigue properties of AZ91 and AZ91–Ca–Y alloys extruded at different temperatures

The commercial AZ91 alloy and nonflammable SEN9 (AZ91–0.3Ca–0.2Y, wt%) alloy are extruded at 300 °C and 400 °C. Their microstructure, tensile and compressive properties, and low-cycle fatigue (LCF) properties are investigated, with particular focus on the influence of the extrusion temperature. In the AZ91 and SEN9 materials extruded at 300 °C (300-materials), numerous fine Mg 17 Al 12 particles are inhomogeneously distributed owing to localized dynamic precipitation during extrusion, unlike those extruded at 400 °C (400-materials). These fine particles suppress the coarsening of recrystallized grains, decreasing the average grain size of 300-materials. Although the four extruded materials have considerably different microstructures, the difference in their tensile yield strengths is insignificant because strong grain-boundary hardening and precipitation hardening effects in 300-materials are offset almost completely by a strong texture hardening effect in 400-materials. However, owing to their finer grains and weaker texture, 300-materials have higher compressive yield strengths than 400-materials. During the LCF tests, {10–12} twinning is activated at lower stresses in 400-materials than in 300-materials. Because the fatigue damage accumulated per cycle is smaller in 400-materials, they have longer fatigue lives than those of 300-materials. A fatigue life prediction model for the investigated materials is established on the basis of the relationship between the total strain energy density ( ∆W t ) and the number of cycles to fatigue failure ( N f ), and it is expressed through a simple equation ( ∆W t = 10· N f −0.59 ). This model enables fatigue life prediction of both the investigated alloys regardless of the extrusion temperature and strain amplitude.

Improvement in tensile strength of extruded Mg–5Bi alloy through addition of Sn and its underlying strengthening mechanisms

Through an investigation of the microstructure and mechanical properties of extruded Mg–5Bi– x Sn (BT5 x, x = 0, 2, 4, and 6 wt%) alloys, this study demonstrates that the addition of Sn to an Mg–5Bi binary alloy significantly improves the tensile strength of the extruded alloy. All the extruded alloys exhibit a typical basal fiber texture and a partially dynamically recrystallized (DRXed) microstructure consisting of fine DRXed grains and coarse unDRXed grains. As the Sn content increases from 0 wt% to 6 wt%, the average size of the DRXed grains decreases from 4.2 to 2.8 μm owing to the increase in the amount of precipitates via their grain-boundary pinning effect. The extruded B5 and BT52 alloys contain numerous Mg 3 Bi 2 precipitates, but their size and number density are smaller and higher, respectively, in the latter alloy. Numerous Mg 2 Sn precipitates as well as Mg 3 Bi 2 precipitates are present in the extruded BT54 and BT56 alloys, and the number density of the Mg 2 Sn precipitates is higher in the latter alloy because of its higher Sn content. The addition of 2 wt% Sn to the B5 alloy significantly improves the yield strength (YS) and ultimate tensile strength (UTS) of the extruded alloy—by 76 and 57 MPa, respectively. This drastic improvement is the combined outcome of enhanced grain-boundary hardening, precipitation hardening, and solid-solution hardening effects induced by the refined DRXed grains, numerous precipitates, and Sn solute atoms, respectively. The further addition of 2 wt% or 4 wt% Sn to the BT52 alloy leads to moderate increments in the YS and UTS of the extruded alloy. Specifically, each addition of 2 wt% Sn increases the YS and UTS by ~26 and ~20 MPa, respectively, which is attributed mainly to the additional precipitation hardening effect induced by the Mg 2 Sn precipitates.

Effective combination of solid solution strengthening and precipitation hardening in NiCrFeWTiAl multi-principal element alloys

Face-centered-cubic (FCC) Multi-principal element alloys (MPEAs) have attracted intensive scientific research interest due to their excellent fracture toughness and ductility. Still, the strengths of single-phase MPEAs are unsatisfactory. Although great progress has been made by utilizing multiple strengthening mechanisms, it remains challenging to take advantage of large-atom solutes and nano-precipitates simultaneously because solutes always partition into the precipitates. In the present work, we successfully achieved an effective combination of solid solution strengthening and precipitation hardening in the NiCrFeWTiAl multi-principal element alloys. Our experimental results showed that W is partitioned into the FCC matrix, while Ti and Al tend to exist in the L12 phase. This controlled elemental partitioning leads to a good combination of solid solution strengthening and precipitation hardening effects and results in good tensile properties at temperatures from 25 ℃ to 760 ℃. The strengthening mechanisms were revealed based on the quantified microstructure analysis. The solid solution hardening of all the solute atoms contributes ∼140 MPa in total, but W mainly contributes to solid solution hardening, and L12 precipitates enhance the yield strength by ∼330 MPa through ordering strengthening.

Wire Oscillating Laser Additive Manufacturing of 2319 Aluminum Alloy: Optimization of Process Parameters, Microstructure, and Mechanical Properties

In this study, a wire oscillating laser additive manufacturing (O-WLAM) process was used to deposit 2319 aluminum alloy samples. The optimization of the deposition process parameters made it possible to obtain samples with smooth surfaces and extremely low porosities. The effects of the deposition parameters on the formability and evolution of the microstructure and mechanical properties before and after heat treatment were studied. The oscillating laser deposition of 2319 aluminum alloy, especially the circular oscillation mode, significantly reduced the porosity and improved the process stability and formability compared with non-oscillating laser deposition. There were clear boundaries between the deposition units in the deposition state, the interior of which was dominated by columnar crystals with many rod- and point-shaped precipitates. After the heat treatment, the θ phase was significantly dissolved. The residual dot- and rod-shaped θ ' phases were dispersedly distributed, exhibiting an obvious precipitation-hardening effect. The samples in the as-deposited state had a tensile strength of 245–265 MPa, an elongation of approximately 12.6%, and an 87 HV microhardness. After heat treatment at 530°C for 20 h and aging at 175°C for 18 h, the tensile strength, elongation, and microhardness reached 425–440 MPa, approximately 10%, and 153 HV, respectively. The performance improved significantly without significant anisotropy. Compared with the samples produced by wire arc additive manufacturing (WAAM), the tensile strength increased by approximately 10%, and the strength and microhardness were significantly improved.

Significant hardness improvement of a low-density Al-Si-Mg-Li-Fe alloy through laser-aging surface treatment

High hardness and low density are desirable merits of materials for wearproof structural applications. This paper develops an Al-10Si-2Mg-0.5Li-0.2Fe alloy that is 3.3% lighter than pure Al, and employs laser-aging surface treatment to improve its hardness. After the treatment, second phase particles from tens of micrometers are transformed to an average size smaller than 15 nm. Hardness of the alloy reaches 194 HV, entering the highest level of Al alloys lighter than pure Al. Meanwhile, corrosion resistance of the alloy in 3.5% NaCl aqueous solution is enhanced by about 34%, due to alleviated micro-galvanic corrosion. Equations are established for evaluating contributions from grain refinement hardening, solid solution hardening and precipitation hardening effects. Accordingly, they are calculated to account for 4.4%, 50% and 45.6%, respectively. This inspires high hardness Al alloy design through taking full advantage of oversaturation and nano-scale precipitation.

Effect of Bi, Sb, and Ti on Microstructure and Mechanical Properties of SAC105 Alloys.

The Sn-Ag-Cu (SAC) solder alloys with a low Ag (Ag < 3 wt.%) content have attracted great attention owing to their low cost, increased ability in bulk compliance, and plastic energy dissipation. However, some of their mechanical properties are generally lower than the SAC alloys with a higher Ag content. Adding alloying elements is an effective approach for improving the mechanical properties of the SAC alloys. In this study, the effect of Bi, Sb, and Ti on Sn-1 wt.%Ag-0.5 wt.%Cu (SAC105) solder alloys was investigated. The SAC solders with four compositions: SAC105-1 wt.%Bi, SAC105-1 wt.%Sb, SAC105-1 wt.%Bi-1 wt.%Sb, SAC105-1 wt.%Bi-1 wt.%Sb-0.4 wt.%Ti were prepared. The microstructure and phase compositions were characterized using electron scanning microscopy, and X-ray diffraction. The thermal properties and wettability were also examined. Uniaxial tensile tests and nano-indentation tests were conducted to evaluate the mechanical properties. The results show that adding Bi or Sb could increase the strength of SAC105 alloys mainly due to the solid solution strengthening effect. The creep resistance of SAC105 alloys was also improved with the additions of Bi and Sb. The co-additions of Bi and Sb into SAC105 alloys exhibit an enhanced creep resistance than that calculated by the theoretical calculation. The further addition of Ti into SAC105-1Bi-1Sb alloys demonstrated a much-improved creep resistance, which could be attributed to the synergistic effects of both solid solution strengthening and the precipitation hardening effects.

Influence of Processing Technology on Creep Damage of Ultrafine-Grained Titanium

This work deals with the influence of the processing technology of ultrafine-grained titanium by the application of severe plastic deformation (SPD) on its degradation processes in creep at elevated temperatures. Commercial grade titanium heats with different content of carbon were processed by multi-stage rolling. Creep tests under constant tensile stress were performed in a protective atmosphere of argon at a temperature of 673 K with application of different stress levels. The microstructure of the fractures creep specimens were analysed by metallographic and fractographic analyses using scanning and transmission electron microscopy (SEM, TEM). Under the same creep loading conditions the heat with higher content of carbon exhibited better creep resistance due to stronger effect of precipitation hardening by titanium carbides.

Characterisation of the multiple effects of Sc/Zr elements in selective laser melted Al alloy

The widespread application of selective laser melting (SLM) fabricated high performance lightweight Al components is hindered by the available commercial alloys due to their limited mechanical properties and processability. The introduction of Sc/Zr elements to the Al matrix for SLM provides conspicuous benefits, including grain refinement, precipitation strengthening and high thermal stability. In the present study, the multiple effects of Sc/Zr elements in SLM fabricated Al alloy are systematically investigated, using the recently developed Al-Mn-Sc alloy as an example. The application of Sc/Zr elements generated an unconventional heterogeneous grain structure characterised by the alternative growth of columnar-equiaxed grains in the molten pool, which effectively avoided the solidification cracks and alleviated the mechanical property anisotropy issues. The formation of the heterogeneous grain structure is mainly attributed to the precipitation of the primary Al3(Sc,Zr) particles which dependent on the local solidification conditions. The post heat treatment was also conducted to clarify the role of Sc/Zr additions on stress relieve effect and precipitation hardening effect. Moreover, the room temperature and elevated temperature mechanical properties of the SLMed Al-Mn-Sc alloy were also evaluated. The fundamental understanding of the Sc/Zr benefits in the SLM fabricated Al alloy is expected to shed light on future high performance Al alloy development specifically for the additive manufacturing process.

Microstructure and mechanical properties of a novel medium Mn steel with Cr and Mo microalloying

In this paper, the effects of Cr and Mo microalloying on the microstructure evolution, mechanical properties, and austenite stability of 0.2C-7Mn steel were investigated at different intercritical annealing temperatures plus the same tempering treatment. Both the yield strength and ultimate tensile strength can be enhanced by nano-sized precipitates and solution hardening effect owing to Cr-Mo addition, while the ductility is well retained. The precipitates are mainly distributed on the ferrite matrix of the (Cr, Mo)-added steel, and directly produce a precipitation hardening effect. Due to the precipitation hardening and solution hardening effects of ferrite, the austenite in the (Cr, Mo)-added steel exhibits a lower mechanical stability, and more strain partitioning among the austenite and ferrite can be borne by the austenite than that in the reference steel, resulting in an accelerating transformation of austenite and a prevailed transformation-induced plasticity effect in the (Cr, Mo)-added steel.

Determination of the effect of artificial aging parameters on dry sliding wear resistance of 6013 aluminum alloy (Al-Mg-Si-Cu)

In this study, the effect of artificial aging parameters, applied to AA6013 aluminum alloys commonly used in the automotive and aerospace sectors, on wear resistance was examined. For this purpose, AA6013 aluminum alloy samples were solutionized at 575 °C for 60 minutes and then they were artificially aged for 2, 4, and 6 hours at 180 and 200 °C temperatures. Mean hardness was measured as 66.6 HV in the solutionized samples taken. It was determined that as a result of artificial aging, α-AlFeMnSi intermetallic phase precipitation were formed between α-Al grains. By the effect of precipitation hardening, an increase in hardness was observed in all artificially aged samples; the highest hardness was found as an average of 149.3 HV in AA6013 samples aged artificially for 2 hours at 200 °C. A general decrease in the friction coefficients of samples aged at both 180 °C and 200 °C was observed along with the artificial aging temperature. The lowest specific wear rate was determined as 3.542x10-3 mm3/Nm in the AA6013 sample aged artificially for 2 hours at 200 °C.

Effect of friction surfacing parameters on microstructure and mechanical properties of solid-solutionized AA2024 aluminium alloy cladded on AA1050

The present study aims to investigate the effect of friction surfacing parameters on the mechanical properties and microstructure of coating fabricated by a solid solutionized consumable rod on the AA1050 substrate. In this regard, the AA2024 aluminum alloy consumable rod was friction surfaced on AA1050 substrate by the rotational speed of 600–1000 rpm, axial feeding rate of 75–200 mm/min, and traverse speed of 100–150 mm/min. The microstructure and mechanical characteristics of coatings showed that increasing the rotational speed, traverse speed, and axial feeding rate results in increasing the unbonded zone extent at the interface of the coating and the substrate. The solid solutionized consumable rod leads to a coating with less width and height in all friction surfacing parameters compared to coatings fabricated by a rod with T3 heat treatment conditions. The average grain size of the coating decreases with decreasing axial feeding rate, increasing traverse speed, and decreasing rotational speed. Although friction surfacing can significantly weaken the fiber texture of consumable rods, the texture intensity in the coatings is slightly changed by changing the friction surfacing parameters. The competitive effect of precipitation hardening and grain refinement mechanisms has a decisive role in the hardness and strength of the coating; however, the influence of the strengthening mechanism through precipitates is much stronger than other mechanisms. Coating fabricated by rotational speed, traverse speed, and axial feeding rate of 1000 rpm, 100 mm/min, and 75 mm/min, respectively, results in the maximum hardness (122.21 VHN0.1) and shear strength (195.65 MPa).