Microstructure Of Aluminum Alloy Research Articles

Preparation of nano surface layer composite (TiB2)p on 6061-T6 Aluminum Alloy via Friction Stir Processing

The current research work is focussed to prepare the nano composite surface layer by reinforcing TiB2 particles on 6061-T6 Aluminum Alloy via Friction Stir Processing (FSP). And also study the influence of nano sized reinforcement particles such as TiB2 (average size is 35 nm) on microstructure and mechanical properties of 6061-T6 Aluminum alloy based surface nano composite fabricated via FSP. The fabricated surface composites have been examined by optical microscope (OM) and scanning electron microscope (SEM) for dispersion of reinforcement particles, thickness of nano composite layer formed on the Aluminum alloy substrate and fracture features. The friction stirred zones were characteristically about the size of the rotating pin, namely width and depth of 8 mm and 4 mm respectively.The depth of surface nano composite layer is measured as 3683.82 µm along the cross section of stir zone of surface nano composite normal to the FSP direction. Microstructures of all the surface composites are revealed that the distribution of reinforcement particles in the nugget zone (NZ). It is observed that increase in the volume percentage of TiB2 reinforcement particle, the microhardness was increased up to 132 Hv and this value is higher than the as received Aluminum alloy’s microhardness (104 Hv). It is also observed that at 4 volume percentage higher tensile properties exhibited as compared with the 2 and 8 vol.%. The observed mechanical properties were correlated with microstructure and fracture features.

Solidification behavior and rheo-diecasting microstructure of A356 aluminum alloy prepared by self-inoculation method

Semisolid slurry of A356 aluminum alloy was prepared by self-inoculation method, and the microstructure and solidification behavior during rheo-diecasting process were investigated. The results indicate that the semisolid slurry of A356 aluminum alloy can be prepared by self-inoculation method at 600 °C. Primary α-Al particles with fine and spherical morphologies are uniformly distributed when the isothermal holding time of slurry is 3 min. Liquid phase segregation occurs during rheo-diecasting process of semisolid slurry and the primary particles (α1) show obvious plastic deformation in the area of high stress and low cooling rate. A small amount of dendrites resulting from the relatively low temperature of the shot chamber at the initial stage of secondary solidification are fragmented as they pass through the in-gate during the mould filling process. The amount of dendrite fragments decreases with the increase of filling distance. During the solidification process of the remaining liquid, the nucleation rate of secondary particles (α2) increases with the increase of cooling rate, and the content of Si in secondary particles (α2) are larger than primary particles (α1). With the increase of cooling rate, the content of Si in secondary particles (α2) gradually increases. The morphologies of eutectic Si in different parts of die casting are noticeably different. The low cooling rate in the first filling positions leads to coarse eutectic structures, while the high cooling rate in the post filling positions promotes small and compact eutectic structures.

Effect of heat treatment on gravity die-cast Sc-A356 aluminium alloy

The effects of scandium addition (0.00 wt.%, 0.2 wt.%, 0.4 wt.% and 0.6 wt.%) and T6 heat treatment on the microstructure and mechanical properties of A356 aluminium alloy have been investigated in the research reported in this paper. The Sc inoculated specimens were prepared by gravity die-casting, according to ASTM B557-06 standard. The cast samples were then subjected to heat treatment at solutionizing temperature of 540 °C for 8 h followed by water quenching and artificial aging at 160 °C for 6 h. The microstructure, microhardness and tensile strength of the heat-treated samples were examined with use of scanning electron microscope (SEM), optical microscope, Vicker’s hardness tester, and Instron static machine respectively. Heat treatment was found to be able to effectively reduce grain size down to 16 μm (0.6 wt.% Sc), from 40 μm (original A356). The tensile strength was significantly improved, up to 338 MPa for heat treated 0.6 wt.% Sc-A356 having been achieved. The microhardness of 118 HV has been obtained for heat treated 0.6 wt.%Sc-A356.

Effect of Laser Cladding Al Ni TiC Powder on Microstructure and Properties of Aluminum Alloy

In this paper, Al/Ni/TiC powders were mixed on the surface of A380 aluminum alloy, by selecting appropriate laser parameters; the cladding layer with good adhesion to the substrate was obtained. The microstructure and properties of the cladding layer under different laser parameters were analyzed. The results show that: the phase composition of the cladding layer is mainly composed of TiC, Al, Ni, C and Ti phases. The hardness of the cladding region is up to 173.3 HV, which is about 2.9 times the matrix (–59.1 HV). The corrosion voltage (–1.8 V) of the cladding layer shifted significantly from the corrosion potential (–1.18 V), the corrosion current density increased, the resistance value decreased and the diameter of the capacitor arc decreased; all these phenomena indicate that the corrosion resistance of the cladding layer is decreased.

Effects of Iron, Manganese, and Cooling Rate on Microstructure and Dry Sliding Wear Behavior of LM13 Aluminum Alloy

ABSTRACTThe presence of Fe in eutectic Al-Si alloy can give rise to formation of a β-Al5FeSi needle-like phase because of low solubility of Fe in this alloy. The brittle nature of this phase leads to decreased mechanical properties of piston alloys, one of which is wear resistance. In this research, to modify β-Fe morphology, Sr and Mn elements were added to the samples prepared from LM13 containing different amounts of Fe. The effect of cooling rate on wear properties of this alloy was also investigated. Results show that the addition of Mn/Fe at aratio of 1/2 can modify the needle-like intermetallics present in the samples containing up to 1.2 wt% Fe. In addition, increasing the cooling rate from 3 to 15°C s−1 refined the eutectic structure and the intermetallics. Hence, it can be considered as another important factor to improve the wear properties of LM13 alloy. To study the wear behavior of this alloy, worn surface and subsurface areas were examined using scanning electron microscopy (SEM) equipped with an energy-dispersive spectrometry (EDS) analyzer.

New Progress on Er-Containing Micro-Alloying Aluminum Alloys

Erbium is an effective micro-alloying element in aluminum alloys and has been investigated intensively. Similar with the addition of Sc in aluminum alloys, nanosized L12-ordered Al3Er precipitates were formed coherently with the matrix in Er-containing micro-alloying aluminum alloys. Further, in the case of the addition of both Er and Zr, core-shell-structured Al3(ZrxEr1−x) precipitates, instead of Al3Er, were observed in a fine dispersion. Those thermally-stable precipitates can refine the grain size, minimize the segregation, homogenize the microstructure, enhance the strength, hinder the recrystallization, and thus improve the comprehensive performance of the aluminum alloys. This paper presents the effect of Er on the microstructure, mechanical properties and thermal stability of aluminum alloys. The research of some typical commercial aluminum alloys containing Er, is also reviewed here.

Effect of Zn, Mg, Cu, Zr on Microstructure and Properties of Laser Welding Aluminium Alloy

A series of Al-6.3Zn-2.3Mg-2.3Cu-0.15Zr alloys with different reduce of Zn, Mg, Cu and Zr were prepared by ingot-metallurgy processing. The metallurgical structure and mechanical properties were investigated by optical microscope, scanning electron microscopy and other equipment. The results indicated that the ingot’s microstructures of the four alloys contain the phrases of η (MgZn2) and θ (Al2Cu), which mostly distribute at the grain boundaries in a shape of continuous network. After extrusion processing, the grain of laser welding aluminium alloy was elongated along the extrusion direction, therefore forming fibrous structures, and meanwhile the second phase particles with different degrees of fragmentation were arranged along the extrusion direction since the microstructure of extruded bars was inherited by the as-cast structure. Zr could significantly inhibit recrystallization of alloy; the recrystallization of the alloy with lower Zr was more obvious. As the content of Zr reduced, the tensile strength of alloy decreased, but the electrical conductivity and hardness increased. When the content of Cu was lower, the hardness were decreased.

Friction-Stir Welding of Zr-Modified AA5083 Sheets in Different Conditions

The effect of friction-stir welding (FSW) on microstructure and mechanical properties of Zr-modified AA5083 aluminum alloy was studied. FSW was observed to lead to the formation of fully recrystallized ultrafine-grained microstructures and preservation of nanoscale dispersoids in stir zone. The joint efficiency of the friction-stir welds for ultimate tensile strength was found to be 94% and 74% in the hot-rolled and cold-rolled preprocessed material conditions. The stir zone microstructure was predicted to be stable against abnormal grain growth during post-weld heat treatment.

Correlation between Fracture Toughness and Quantitative Characterization of Microstructure in 7055 Aluminium Alloy

Microstructure of high strength aluminum alloy have determinant effect on the properties, thus an effort has been made to investigation the relationship between fracture toughness and quantitative characteristics of microstructure in high strength aluminum alloy. Fracture toughness was tested for aluminum alloy specimens with various microstructure. The corresponding microstructure was observed by optical metallography and electron back-scattered diffraction, and quantitative characterization was conducted by further analysis of result obtained. Correlation between fracture toughness and parameters included grain size, percentage of recrystallization, substructure content and area fraction of residual phases was investigated. It was shown that percentage of recrystallization was a crucial factor for the fracture toughness, and correlations were established with proper and reasonable correction.

Response of Microstructure in High Strength Aluminium Alloy to Graff Sargent Etchant

The response of microstructure in high strength Al-Zn-Mg-Cu aluminum alloy 7055 to Graff Sargent etchant was investigated. It was found that grain boundaries and subgrain boundaries were easily corroded due to presence of η phase, and grain boundaries were corroded more rapidly than subgrain boundaries. The grain structure could be revealed quite clearly after immersion for about 15s. S (Al2CuMg) and Al7Cu2Fe phase were quite stable during immersion if the time was not very long. A dealloying for Al/Mg in the S and Al7Cu2Fe phase was found after long time immersion. Prolonged immersion resulted in serious corrosion of subgrain boundaries, consequently separation of fine subgrains.

Microstructure and Mechanical Properties of Semi-Solid Die-Cast A356 Aluminum Alloy

The present work deals with the relationship between microstructure and mechanical properties of A356 aluminum alloy which was produced via thixocasting process under different casting conditions. Feedstock billets were heated to a target temperature to obtain a semi-solid slurry with the required solid fraction. Some billets were heated to a fully-melted condition. In order to obtain fine and spheroidized Al grains, some billets for the partially melting were compressed axially by 33% at a room temperature before heating. The completely-melted and partially-melted slurries were die-cast by using a die-cast machine, and hour glass-shaped rod-type tensile specimens and small-size plate-type tensile specimens were obtained. Small cubic specimens were also collected from the die-cast products for microstructural evaluation. They were polished, and etched by Weck’s reagent. The partially-melted specimen which was compressed before heating shows the spherical Al grains. But the grain of the strain-free partially-melted specimen exhibited complicated morphology. The fully-melted specimen shows the fine and dendrite structure.

Evaluation of microstructure of A356 aluminum alloy casting prepared under vibratory conditions during the solidification

The objective of this investigation was to evaluate the effect of vibrations (during solidification) on the metallurgical properties of A356 aluminum casting. Mechanical vibrations were applied to A356 aluminum alloy through set up. A356 melt has been subjected to mechanical vibration with the frequency range from 0 to 400 Hz with constant amplitude 5 µm. Grain refinement was obtained through mold vibration. Metallurgical properties were examined through optical microstructure, tensile fracture scanning electron microscope (SEM) and SEM image of test specimens prepared under different conditions of solidification. Results indicate that mold vibration effectively modified the microstructure of A356 casting and it has uniform and smaller grain size with fibrous silicon particle than nonvibrated casting. Grain refinement results increase in mechanical properties with increase in frequency of vibration of mold during the solidification. SEM micrograph of tensile fracture surface was carried out to study the influence of microstructure on fracture mode. SEM image of tensile fractured surface shows transgranular cleavage facets due to fracture of primary silicon particles. Fractures are brittle in nature so observation indicates low ductility and brittle fracture.

Microstructure of Aluminium Alloys Casting Intended for Cyclical Thermal Stress

Microstructure of Aluminium Alloys Casting Intended for Cyclical Thermal Stress

Correlation between microstructure, tensile properties and fatigue life of AA1050 aluminum alloy processed by pure shear extrusion

This research is focused on the influence of multiple passes of pure shear extrusion (PSE) on grain refinement and evolution of tensile properties in AA1050 alloy. It is observed that the average cell size reduces and the misorientation angle increases with increasing number of PSE passes. High fractions of elongated grains are observed in the microstructures of the samples deformed by 1, 2 and 3 PSE passes. However, the fraction of elongated grains reduces by increasing number of PSE passes and diminishes at the 4-pass of PSE. In fact, by increasing the number of PSE passes, more homogeneous grain refinement occurs which is evidenced by formation of equiaxed cell structures with remarkable percentage of high angle grain boundaries. The most significant increase in yield and tensile strength occurs at the first pass of PSE. Strengthening continues with further PSE processing while elongation gradually improves which is attributed to reducing cell size and increasing the fraction of high angle grain boundaries. Despite of increasing elongation and strength, the fatigue life of the samples continuously reduces with further PSE processing. This is attributed to occurrence of cyclic softening in deformed samples with ultra-high strength.

Study on Mechanical Properties and Microstructure of Aluminium Alloy 63401 Reinforced with Alumina Powder

Objectives: This paper includes the study of mechanical properties and microstructure characterization of aluminium alloy 63401 reinforced with alumina powder of different mesh size and different weight percentage. Methods: Fabrication of composite material is done by stir casting process because it is the cheapest way to fabricate mass samples. Different grain size of (149μm, 74μm, 37μm) and different weight percentage of (3%, 6%, 9%) have been used in this experiment. Findings: The tensile strength, impact strength and hardness of the composite material produced by reinforcing alumina powder increases with increase in the percentage of alumina powder and also vary with particle size of alumina powder. Applications: This type of composite material can be used in aerospace and automobile sectors.

Study on Mechanical Properties and Microstructure of Aluminum Alloy 63401 Metal Matrix Composite Reinforced with Silicon Carbide Powder

Objectives: The present research examine the mechanical properties and microstructure of aluminum alloy 63401 metal matrix composite reinforced with silicon carbide powder of different wt% i.e. 3%, 6% and 9% and different grain size. Different weight percent of SiC i.e. 3%, 6% and 9% with different grain size of 177 μm, 149 μm and 74 μm. Methods: The mechanical properties i.e. hardness, tensile strength and impact strength were studied by preparing the required samples by stir casting method. Findings: From the obtained results we found that more the weight percentage of SiC powder, impact strength, tensile strength and hardness increases but the percentage elongation decreases with increase in weight percentage of SiC and increases with decrease in grain size of SiC. Also microstructure shows the nearly distribution of reinforcement material. Applications: They can be used in making body parts of vehicles having great impact strength. Making different parts of aeroplanes and also used in producing bus bars of higher strength.

The Microstructure and Compressive Properties of Aluminum Alloy (A356) Foams with Different Al-Ti-B Additions

Closed-cell aluminum alloy (A356) foams with different percentages of Al-Ti-B are prepared by melt foaming method, using Ca and TiH 2 as thickening agent and foaming agent, respectively. SEM and Quasi-static compression tests are performed to investigate the effect of Al-Ti-B on the microstructure and compressive properties of aluminum alloy (A356) foams. The results show that foams with Al-Ti-B percentage of 0.3 wt.% possess good combinations of micro hardness, yield strength, plateau strength, densification strain and energy absorption capacity under the present conditions. The reasons are mainly due to the foams with Al-Ti-B percentage of 0.3 wt.% possess optimal eutectic Si morphology (with eutectic Si existing in the forms of particles or short fiber). DOI: http://dx.doi.org/10.5755/j01.ms.22.3.8559

Effect of thermomechanical treatment on the microstructure, phase composition, and mechanical properties of Al–Cu–Mn–Mg–Zr alloy

The effect of the thermomechanical treatment on the microstructure, phase composition, and mechanical properties of heat-treatable AA2519 aluminum alloy (according to the classification of the Aluminum Association) has been considered. After solid-solution treatment, quenching, and artificial aging (T6 treatment) at 180°C for the peak strength, the yield stress, ultimate tensile strength, and elongation to failure are ~300 MPa, 435 MPa, and 21.7%, respectively. It has been shown that treatments that include intermediate plastic deformations with degrees of 7 and 15% (T87 and T815 treatments, respectively) have a significant effect on the phase composition and morphology of strengthening particles precipitated during peak aging T8X type, where X is pre-strain percent, treatments initiate the precipitation of significant amounts of particles of the θ′- and Ω-phases. After T6 treatment, predominantly homogeneously distributed particles of θ″-phase have been observed. Changes in the microstructure and phase composition of the AA2519 alloy, which are caused by intermediate deformation, lead to a significant increase in the yield stress and ultimate tensile strength (by ~40 and ~8%, respectively), whereas the plasticity decreases by 40–50%.

Microstructure and Salt Fog Corrosion Behaviour of AA2219 Friction Stir Welded Aluminium Alloy

Microstructure and Salt Fog Corrosion Behaviour of AA2219 Friction Stir Welded Aluminium Alloy

Effect of Intensive Plastic Deformation on Microstructure and Mechanical Properties of Aluminum Alloys

In work it was studied the influence of intensive plastic deformation on structure and mechanical properties of aluminum alloys. Intensive plastic deformation was carried out by using equal-channel angular extrusion. It is shown that the most efficient angle of intersection of the channels is the angle of Φ=120°, which ensures defect-free parts at the highest possible level of accumulated strain (e=8). It is established that the intensive milling grain structures in aluminum alloys AMG6 and AMC occurs at ECAE-12 passes, while the intersection angle of the channels of 120°. After ECAE-12 in aluminum alloys the grain refinement reaches to the size of ∼⃒1.0-1.5 gm. It is determined that as a result of equal channel angular pressing, the microhardness of alloy AMG6 increases almost 4 times in comparison with the initial state, the microhardness of alloy AMC increases by almost 4.5 times in comparison with the initial state. It is shown that ECAE-12 mass loss is reduced to 5.4 and 5.6 mg, which shows an increase in wear-resistance of aluminum alloys AMG6 and AMC 13-14 %.