Top PDF Microstructure and properties of Mg-Al binary alloys

Microstructure and properties of Mg-Al binary alloys

Microstructure and properties of Mg-Al binary alloys

Mg-Al binary alloys containing different amounts of added Al were prepared using commercial pure magnesium (99.8 %) and commercial pure aluminum (99.9 %), the chemical compositions of which are shown in Table 1. The alloys were melted using a low-carbon steel crucible, with a capacity of 12 kg, in an electrical resistance furnace under the protection of RJ-1 flux. The melt temperature was fixed at 750 ņ. When the melt temperature reached 750ņ different amounts of pure Al, ranging from 1 % to 9 %, were added. Then the melt was stirred for 2 min and held at 750ņ for 10 min to make sure that the Al was completely dissolved. Finally the melt was cast into a Φ 30 mm ġ 50 mm sand mold, or a permanent mold for the hot cracking test. Before casting, the permanent mold temperature was kept at about 300 ņ. The schematic representation of the hot cracking permanent mold is shown in Fig.1.The metallographic samples were sectioned at a distance of 25 mm from the bottom of each sand-cast sample, and then subjected to a solution treatment at 415ņ for 14 h, polishing, and etching. The average grain size of each sample was measured following the Heyn Lineal Intercept Procedure described in ASTM E112-95 specification. The morphologies of α-Mg dendrites in the hot cracking fractographs with a diameter of 8 mm and the eutectic microstructure of sand-cast samples were examined by using a CSM-950 scanning electron microscope. The hot cracking resistance property of the Mg- Al binary alloys was evaluated using the critical diameter Abstract: The effects of different amounts of added Al, ranging from 1 % to 9 %, on the microstructure and properties of Mg-Al binary alloys were investigated. The results showed that when the amount of added Al is less than 5%, the grain size of the Mg-Al binary alloys decreases dramatically from 3 097 µm to 151 µm with increasing addition of Al. Further addition of Al up to 9% makes the grain size decrease slowly to 111 µm. The α-Mg dendrite arms are also refined. Increasing the amount of added Al decreases the hot cracking susceptibility of the Mg-Al binary alloys remarkably, and enhances the micro-hardness of the α-Mg matrix.
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Unique microstructure and excellent mechanical properties of ADI

Unique microstructure and excellent mechanical properties of ADI

Ferrite has a non-close packed bcc lattice with a lattice parameter of 0.287 nm and a total of 48 slip systems. The movement of dislocations in ferrite is therefore easy and this makes it soft and ductile. Austenite has a close packed fcc lattice with a lattice parameter of 0.364 nm and a total of 12 slip systems. Although the total slip systems in ferrite are more than for austenite, the critical Peierls force to move a dislocation is less in an fcc lattice than that in a bcc lattice, therefore austenite is also very soft and ductile. Austenite is normally unstable at room temperature, but under certain conditions it is possible to obtain stable austenite at room temperature by the use of alloys. Cementite has an orthorhombic lattice with approximate parameters 0.451 65, 0.508 37 and 0.672 97 nm. There are twelve iron atoms and four carbon atoms per unit cell, corresponding to the formula Fe 3 C. Each carbon atom is surrounded by eight iron atoms and each iron atom is connected to three carbon atoms. Cementite is a type of interstitial compound and is a Fig.2 Comparison of ADI properties with steels and
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An Experimental Study of the Solidification Thermal Parameters Influence upon Microstructure and Mechanical Properties of Al-Si-Cu Alloys

An Experimental Study of the Solidification Thermal Parameters Influence upon Microstructure and Mechanical Properties of Al-Si-Cu Alloys

The alloys were prepared in a graphite-clay crucible in a muffle-type electric furnace using commercially pure metals, which were analyzed by the X-ray spectrometry technique using a Spectro Spectromaxx Spectrometer (Table 1). Four casting leaks were performed for each of the alloys, all of them with a casting temperature of 700 ºC. The first ingot was used to analyze the solidification kinetics and preparation for micrographic analysis and the other three ingots were Table 1. Chemical composition of the raw materials in weight %

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Effect of Overageing Conditions on Microstructure and Mechanical Properties in Al–Si–Mg Alloy

Effect of Overageing Conditions on Microstructure and Mechanical Properties in Al–Si–Mg Alloy

w w w . a j e r . o r g Page 322 The needle-like monoclinic β phase is considered to be the most effective strengthening precipitate among all types of precipitates in AlMg–Si alloys. Its composition is normally accepted as Mg5Si6 [25, 29]. Natural aging (NA) can significantly depress the hardening kinetics and the maximum strength obtained in subsequent artificial aging of AlMg–Si alloys. This phenomenon, also well-known as “negative NA effect”, has attracted a lot of interest because of its link with practical industrial process [30–34]. However, overageing has adverse effect on this alloy [23]. So, it is very beneficial to have clear concept regarding the actual state of mechanical properties at that severe ageing condition. In this research work change of microstructure and mechanical properties with different ageing time have been investigated. Thus this project has a potential of determining the actual state of strength and hardness when any Al-Si alloy parts experience any elevated temperature for any length of time.
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Study on microstructure and properties of Mg-alloy surface alloying layer fabricated by EPC

Study on microstructure and properties of Mg-alloy surface alloying layer fabricated by EPC

The previous studies mainly concentrated on the solid phase diffusion, however, the diffusion layer is too thin to protect the substrate effectively. Mg-alloy surface alloying through casting technology can make use of some advantages of casting, for instance, the good penetrability of molten metal, and the melt permeating the alloying coating after pouring the melt. The powder particles melt and diffuse within the interface between the substrate and particles. At the interfaces between the alloying coating and the melt, the occurrence of metallurgical fusion gives birth to the formation of an alloying layer on the matrix, whose thickness can reach hundreds of microns. The present surface alloying investigation mostly focuses on cast iron, cast steel and other high melting point metals. For magnesium alloys there is little research in this aspect, and related literatures and reports are not much so far.
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Influence of Si Coating on Interfacial Microstructure of Laser Joining of Titanium and Aluminium Alloys

Influence of Si Coating on Interfacial Microstructure of Laser Joining of Titanium and Aluminium Alloys

The distribution profiles of the Ti, Al and Si elements at dissimilar joining with silicon film deposited on titanium alloy for 1 and 2 hours are presented in the Figures 8-a and 8-b, respectively, in comparison with a condition without silicon introduction (Figure 8-c). A significant decrease of the titanium diffusion width to aluminium alloy is observed with the introduction silicon in the joining interface. The results are in agreement with the obtained in the microscopy analysis of this region (Figure 7). Moreover, the silicon deposition time influenced the layer thickness formed after joint process. A thin layer is formed with the silicon introduction, in the order of 3 µm, if compared to joint process without silicon, up to five times thicker. Table 2 summarizes the phase compositions in different points of the curve (Figure 8-c), denoted by P1-P4. Based on the Al- Si binary phase diagram (Figure 9 25 ) the possible phases of
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Mat. Res.  vol.20 número3

Mat. Res. vol.20 número3

The binary diagrams have limited application because commercial aluminium alloys always contain appreciable amounts of iron, which signiicantly afect the microstructure. Because of a greater tendency of the Fe atoms to segregate, the intermetallics formed during solidiication contain relatively more Fe than Mn. Al–Mn–Fe and Al–Mn–Fe–Si alloys are important commercial aluminium alloys. They have been used in many industrial sectors and in particular in the rapidly growing aluminium heat exchanger market. The previous works mainly revealed the inluences of the Mn and Fe content on the type and size of diferent Al-Mn and Al-Mn-Si alloys 7-9 or the cooling rate on the evolution of
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Microstructural and mechanical properties of gravity-die-cast A356 alloy inoculated with yttrium and Al-Ti-B grain refiner simultaneously

Microstructural and mechanical properties of gravity-die-cast A356 alloy inoculated with yttrium and Al-Ti-B grain refiner simultaneously

Aluminium alloys constitute a significant proportion of lightweight metals used in various industries for applications ranging from automotive components to aerospace parts etc [4]. There is always a constant need to improve the microstructure and its inherent mechanical properties of aluminium alloys castings due to the increasing awareness of reducing green house emissions by using lightweight materials in automotive industries. Aluminium alloys are known to have excellent strength to weight ratio compared with other conventional metals like steels. A356 is one of the most widely used aluminium alloys in many industrial applications because of its excellent castability, corrosion resistance and good mechanical properties. It has lower production cost, fast machining rate and good recyclability. Typical commercial grain refiners use to refine A356 aluminium castings are Al-Ti-B and Al-Ti-C master alloys. The efficiency of these grain refiners can be easily undermined by alloying elements like Zr and V [5]. In recent years, yttrium has been regarded as a promising element in superalloys for its ability to improve creep property and oxidation resistance of cast stainless steel [6-7]. However, very little work was done to investigate the effect of yttrium on the grain refining efficiency of Ti-B based grain refiner in A356 casting. Therefore, the research presented by this paper intends to study the effect of rare earth yttrium on the grain refinement efficiency of Al-T-B master alloy by using gravity die casting as the casting process.
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Study of Microstructure and Thermal Properties of the Low Melting Bi-In-Sn Eutectic Alloys

Study of Microstructure and Thermal Properties of the Low Melting Bi-In-Sn Eutectic Alloys

Temperatures and latent heats of melting were determined by simultaneous thermal analyser SDT Q600 (TA Instruments). Samples weighing about 50 mg were investigated by performing 5 heating cycles using the heating rate of 5 °C/min in the temperature interval from room temperature up to 150 °C. The reference material was empty alumina crucible. Before DSC measurements temperature and heat calibrations were performed using the pure metal standards (Bi, In and Zn) under the measurement conditions.

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Effect of V and Nb additions on microstructure, properties, and deformability of Ti-45Al-9 (V, Nb, Y) alloy

Effect of V and Nb additions on microstructure, properties, and deformability of Ti-45Al-9 (V, Nb, Y) alloy

T he TiAl-based alloys are promising materials for the use in advanced propulsion systems of aircraft and automobile engine parts, due to the combination properties of low density, high speciic strength, high speciic stiffness, good creep strength up to 700℃, and better high temperature oxidation resistance than titanium alloys [1-3] . However, the extensive applications of TiAl based alloys have been limited by low ductility and poor formability at room temperature [4] . Recently, Kim and Dimiduk proposed β/γ-TiAl alloys that exhibited excellent formability above 1,100℃ [5] . Such alloys can be manufactured through the beta-solidiication process, and exist experimentally within a broad composition range of Ti-(40-45)Al-(2-7)Nb-(1-9)(Cr, Mn, V, Mo)-(0-0.5) (B, C) (in wt.% hereinafter). In this study, Ti-45Al-9(V, Nb, Y) alloys with different V/Nb ratio (i.e. 1, 1.5, 2 and 3.5) were prepared; the microstructures, mechanical properties, hot deformation and oxidation behaviors of these alloys were systematically studied.
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Corrosion behavior of as-cast binary Mg-Bi alloys in Hank's solution

Corrosion behavior of as-cast binary Mg-Bi alloys in Hank's solution

Abstract: Biodegradable Mg-xBi (x = 3, 6 and 9wt.%) alloys were fabricated by ingot casting, and the change of corrosion behavior of the alloys in the Hank's solution was analyzed with respect to the microstructure using optical micrograph (OM), X-ray diffraction (XRD), scanning electron microscope (SEM) equipped with an energy dispersive X-ray spectrometer (EDS), electrochemical and immersion tests. The results show that the microstructures of the as-cast Mg-Bi alloys mainly consisted of dendritic α-Mg grains and Mg 3 Bi 2 phase in
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Influence of thermo hydrogen treatment on microstructure and mechanical properties of Ti-5Al-2.5Sn ELI alloy

Influence of thermo hydrogen treatment on microstructure and mechanical properties of Ti-5Al-2.5Sn ELI alloy

T itanium alloys are widely used in various fields because of their characteristics of low density, high strength, corrosion resistance and high temperature resistance. Ti-5Al-2.5Sn ELI alloy is a kind of important structural material used under low temperature in the aerospace field. To meet the need of Ti-5Al-2.5Sn ELI alloy castings with high strength and high fatigue resistance, this work intends to research the inluence of thermo hydrogen treatment (THT) on this alloy.

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Efeito de Diferentes Tratamentos Térmicos na Microestrutura e Propriedades Mecânicas de Ligas Al-Si Fundidas por Gravidade / Effect of Different Heat Treatments on the Microstructure and Mechanical Properties of Al-Si Alloys Cast by Gravity

Efeito de Diferentes Tratamentos Térmicos na Microestrutura e Propriedades Mecânicas de Ligas Al-Si Fundidas por Gravidade / Effect of Different Heat Treatments on the Microstructure and Mechanical Properties of Al-Si Alloys Cast by Gravity

Braz. J. of Develop., Curitiba, v. 6, n.4,p.18681- 18696 apr. 2020. ISSN 2525-8761 study the effect of heat treatments T6 and T4 on the microstructure and mechanical properties of A356 and H1SH alloys. The alloys were casting by gravity and heat treated, with alloy A356 treated by T6 and alloy HS1H by T4 in the industrial. Initially, chemical analysis was performed to prove the chemical composition of the two alloys. The chemical composition showed that the alloy A356 contains 7.610% Si and the alloy H1SH presents 5.275% Si. The optical microscopy of the samples revealed dendritic microstructures rich in aluminum and spheroidized precipitates rich in silicon. The image analysis showed that the alloy A356 presented 86.632% of phase (α-Al), while the H1SH alloy presented 90.840%. The image analysis also showed that the alloy A356 had precipitates greater than those of the alloy H1SH. By the tensile test, it was found that the HS1H alloy presented higher values of tensile strength, however, the yield strength and elongation of the A356 alloy were higher. The Víckers microhardness demonstrated that the HS1H alloy showed greater hardness in relation to the A356 alloy.
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Microstructure and mechanical properties of Mg-6Al magnesium alloy with yttrium and neodymium

Microstructure and mechanical properties of Mg-6Al magnesium alloy with yttrium and neodymium

The microstructures of the alloys after solution and aging treatment are shown in Fig.2. As can be seen in Fig. 2(a), a -Mg 17 Al 12 phases of Mg-6Al magnesium alloy precipitate both inside grains and at grain boundaries after solid solution and aging treatment. These precipitates are scattered at the grain boundaries in coarse bulk and inconsecutive network, while inside the grains are in fine particle structure. From the phase diagram of Mg-Al binary system [7−8] , it can be explained that when Mg-6Al magnesium alloys are heated for solid solution treatment at 420℃, the supersaturated a-Mg solid solutions of the alloys are first formed, then the solid
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Mat. Res.  vol.16 número1

Mat. Res. vol.16 número1

Effect of calcium addition on microstructure, hardness value and corrosion behavior of five different Mg-xCa binary alloys (x = 0.7, 1, 2, 3, 4 wt. (%)) was investigated. Notable refinement in microstructure of the alloy occurred with increasing calcium content. In addition, more uniform distribution of Mg 2 Ca phase was observed in α-Mg matrix resulted in an increase in hardness value. The in-vitro corrosion examination using Kokubo simulated body fluid showed that the addition of calcium shifted the fluid pH value to a higher level similar to those found in pure commercial Mg. The high pH value amplified the formation and growth of bone-like apatite. Higher percentage of Ca resulted in needle-shaped growth of the apatite. Electrochemical measurements in the same solution revealed that increasing Ca content led to higher corrosion rates due to the formation of more cathodic Mg 2 Ca precipitate in the microstructure. The results therefore suggested that Mg-0.7Ca with the minimum amount of Mg 2 Ca is a good candidate for bio-implant applications.
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Interconnection between microstructure and microhardness of directionally solidifi ed binary Al-6wt.Cu and multicomponent Al-6wt.Cu-8wt.Si alloys

Interconnection between microstructure and microhardness of directionally solidifi ed binary Al-6wt.Cu and multicomponent Al-6wt.Cu-8wt.Si alloys

It is well known that the primary dendritic arm spacings are dependent on the solidification thermal parameters such as growth rate (V L ) and cooling rate (T R ), all of which vary with time and position during solidifi cation. In order to determine more accurate values of these parameters, the results of experimental thermal analysis have been used to determine the displacement of the liquidus isotherm, i.e., the thermocouples readings have also been used to generate a plot of position from the metal/mold interface as a function of time corresponding to the liquidus front passing by each thermocouple. The thermocouples readings (Figure 1b) have been used to generate a plot of position from metal/mold interface (P) as a function of time (t) corresponding to the liquidus front passing by each thermocouple. A best fi tting curve on these experimental points has generated a power function of position as a function of time, i.e., P = f (t). This has been obtained by the Origin 8.0 software. The method has been detailed in recent article (Carvalho et al. 2013). The derivative of this function with respect to time has yielded values for V L . The T R profi le was calculated by considering the thermal data recorded immediately after the passing of the liquidus front by each thermocouple. The method used for measuring the tip cooling rate was detailed by Rocha et al. (2003).
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Mat. Res.  vol.18 número6

Mat. Res. vol.18 número6

applied FSW for joining of two AA7075 plates using SiC reinforcements along the joint line and found promising results from the standpoint of impact toughness. They reported that excellent bonding between reinforcements and the substrate was the reason of positive effect of SiC particles on impact energy absorption. No study to date, however, addressed the joining of dissimilar aluminum alloys based on the foregoing method. Accordingly, the main purpose of this study is to examine the effects of Al 2 O 3 particles on the microstructure, corrosion properties, and fracture toughness of AA7075/AA5083 joint performed via FSW. Excellent corrosion resistance of AA7075-T6 and AA5083-H116 aluminum alloys, along with a unique combination of mechanical properties are the reasons why authors have picked up these alloys as the substrates 14-16 . Moreover, in
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Effect Of Process Parameters On Mechanical Properties Of Friction Stir.Welded Joint Of Two Similar &Dissimilar Al-Alloys

Effect Of Process Parameters On Mechanical Properties Of Friction Stir.Welded Joint Of Two Similar &Dissimilar Al-Alloys

The microstructure of the different weld regions of the FSW of similar material in sample no. 2 through 800 rpm, welding speed 13 mm/min and tool diameter 30mm are shown from figure no 17(a-d) . Though the weld undergoes considerable amount of thermal cycle. Figure17 (a) microstructure of weld region shows the distribution of the precipitates is uniform throughout the weld region. Severe plastic deformation was observed and the precipitates were be destroyed and also some re-precipitation was observed. Figure17 (b) shows , formation of some oxide layer at either at the advancing side or at the retreating side of the weld sample was observed; forming some uneven boundary between the weld centre and the TMAZ and thus making some differentiation between them. A nugget region was observed near the bottom root portion of the weld centre region which is shown in figure 17 (c). The stirred zone has higher hardness compared with HAZ and TMAZ because of smaller grain size at this zone. .The HAZ formed on the both the side of the weld, i.e. advancing and retreating side of weld. The reason behind formation of the heat affected zone is temperature difference across the weld. Since the alloy plate was at room temperature before welding. When the welding was done by the rotation of tool, there was substantial increase in temperature due to the friction generated between the tool and work piece and due to the plastic deformation of work piece. Hence, grain growth was observed in the HAZ which is shown figure17 (d).
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Mat. Res.  vol.15 número3

Mat. Res. vol.15 número3

at ambient temperatures has limited their applications. Alloy design and development to improve their low-temperature ductility have become the major challenge for this alloy system. Depending on the composition and heat-treatment procedure, four microstructures of γ-TiAl, i.e., near γ (NG), duplex (DP), near lamellar (NL) and fully lamellar (FL), can be obtained. It has been established that those alloys with a fine fully lamellar (FL) microstructure possess good balanced mechanical properties 7,8 . Actually, the

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