As-cast Mechanical Properties Research Articles

Effect of Ce Addition on Microstructure, Thermal Conductivity, and Mechanical Properties of As-Cast and As-Extruded Mg-3Sn Alloys.

In the present research, the impacts of Ce additions at various concentrations (0, 1.0, 3.4, and 4.0 wt.%) on the evolution of the microstructure, mechanical properties, and thermal conductivity of as-cast and as-extruded Mg-3Sn alloys were investigated. The findings demonstrate that adding Ce caused the creation of a new ternary MgSnCe phase in the magnesium matrix. Some new Mg17Ce2 phases are generated in the microstructure when Ce levels reach 4%. The thermal conductivity of the Mg-3Sn alloy is significantly improved due to Ce addition, and the Mg-3Sn-3.4Ce alloy exhibits the highest thermal conductivity, up to 133.8 W/(m·K) at 298 K. After extrusion, both the thermal conductivity and mechanical properties are further improved. The thermal conductivity perpendicular to the extrusion direction of Mg-3Sn-3.4Ce alloy could achieve 136.28 W/(m·K), and the tensile and yield strengths reach 264.3 MPa and 227.2 MPa, with an elongation of 7.9%. Adding Ce decreases the dissolved Sn atoms and breaks the eutectic α-Mg and Mg2Sn network organization, leading to a considerable increase in the thermal conductivity of as-cast Mg-3Sn alloys. Weakening the deformed grain texture contributed to the further enhancement of the thermal conductivity after extrusion.

Microstructure and Mechanical Properties of As-Cast and Hot Extruded–Sheared ZG61 Alloy

Microstructure and Mechanical Properties of As-Cast and Hot Extruded–Sheared ZG61 Alloy

Comparison of microstructure, damping capacity, and mechanical properties of cast and deformation processed Fe17Mn alloys

There were few works on cast FeMn damping alloys although many studies have been conducted on deformation processed (DP) counterparts. In this study, we investigated the differences in damping and mechanical properties of as-cast and as-DP Fe17Mn alloys and the effect of solution treatment at 1050℃ (ST) on their properties. The as-cast Fe17Mn alloy demonstrated a higher damping capacity but lower strength than the as-DP Fe17Mn counterpart. As much as 18 % of the BCC phase was distributed as dendrite in the Mn-depleted region of the as-cast Fe17Mn alloy. The DP Fe17Mn alloy inherited some BCC phase with less than 1 % content formed during the casting. The ST further improved the damping capacity and plasticity but decreased the strength in both the cast and DP Fe17Mn alloys. After the ST, the cast Fe17Mn alloy also showed good mechanical properties, with tensile strength up to 645 MPa and fracture up to 40 %. Our results shed light on the potential application of cast Fe17Mn alloy in mechanical components.

Effect of Mischmetal Addition on Microstructure and Mechanical Properties of As-Cast and As-Rolled Mg–Sn–Ca Alloys

The microstructures and mechanical properties of Mg–3Sn–0.1Ca–xMM (mischmetal, x = 0.3, 0.6, and 0.9 wt.%) alloys were investigated. Optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction spectroscopy (XRD) were used to characterize the microstructures and phase constitutions of the cast and rolled alloys. Room temperature tensile tests were conducted to obtain the mechanical properties and macro-textures to evaluate the texture weakening effect results of the MM. The results show that an abundance of second phase formed, confirmed as the (Ca,MM)MgSn phase, and the volume fraction increased with the increasing MM addition. The tensile yield strength of the as-cast alloys increased with the MM addition, but the elongation decreased. All of the rolled Mg–3Sn–0.1Ca–xMM alloys showed a strong basal texture, and only slightly decreased in intensity after annealing treatment due to the particle-stimulated nucleation of recrystallization. The as-annealed Mg–3Sn–0.1Ca–0.6MM alloys exhibited the highest tensile strengths of 266.5 ± 3.3 MPa and 136.1 ± 3.7 MPa, which are mainly ascribed to grain refinement strengthening, Orowan strengthening and texture strengthening.

A novel Fe-rich Fe-Cr-Ni-Si-Al high-entropy alloy with low-cost and outstanding as-cast mechanical properties

A novel Fe2CrNiSi0.3Al0.28 high-entropy alloy (HEA) was designed and produced via arc-melting. This Co-free Fe-rich HEA mainly consists of bulky body-centered cubic (BCC) structure and branches of fine needle-like face-centered cubic (FCC) particles. Moreover, this as-cast HEA exhibits the ultimate tensile strength (UTS) of ∼1.3 GPa and plasticity of ∼9%. Compared to the typical ductile as-cast HEAs, it shows among the highest UTS and lowest cost. Heterostructure exhibits positive influence on its high mechanical properties. This work provides a novel insight for propelling broad applications of HEAs.

Microstructure and mechanical properties of as-cast (CuNi)100−xCox medium-entropy alloys

Microstructure and mechanical properties of non-equiatomic (CuNi)100−xCox (x=15, 20, 25 and 30, at.%) medium-entropy alloys (MEAs) prepared by vacuum arc-melting were investigated. Results show that all the as-cast MEAs exhibit dual face-centered cubic (fcc) solid-solution phases with identical lattice constant, showing typical dendrite structure consisting of (Ni, Co)-rich phase in dendrites and Cu-rich phase in inter-dendrites. The positive enthalpy of mixing among Cu and Ni-Co elements is responsible for the segregation of Cu. With the increase of Co content, the volume fraction of (Ni, Co)-rich phase increases while the Cu-rich phase decreases, resulting in an increment of yield strength and a decrement of elongation for the (CuNi)100−xCox MEAs. Nano-indentation test results show a great difference of microhardness between the two fcc phases of the MEAs. The measured microhardness value of the (Ni, Co)-rich phase is almost twofold as compared to that of the Cu-rich phase in all the (CuNi)100−xCox MEAs. During the deformation of the MEAs, the Cu-rich phase bears the main plastic strain, whereas the (Ni, Co)-rich phase provides more pronounced strengthening.

Effect of Rolling Deformation on Microstructure and Mechanical Properties of As-Cast and Rolled ZM21 Magnesium Alloy

Effect of Rolling Deformation on Microstructure and Mechanical Properties of As-Cast and Rolled ZM21 Magnesium Alloy

Improvement of mechanical properties of in situ Mg-Si composites via Cu addition and hot working

The synergistic effects of copper addition and hot extrusion process on the modification of microstructure and enhancement of mechanical properties of a common in situ hypereutectic Mg-Si metal-matrix composite were studied. It was revealed that Cu addition at the microalloying level of 0.5 wt% was very effective in modifying the primary and eutectic Mg2Si phases, which led to the enhancement of the as-cast mechanical properties. Further Cu additions (2, 4.5, 8, and 15 wt%) led to the appearance of the α-Mg/Mg2Cu eutectic constituent and distinct α-Mg regions with the disappearance of Mg2Si eutectics in the ingots, which was ascribed to the change in the solidification path. Contrary to the favorable effect of Cu at the micro-addition level, higher additions led to poor tensile properties due to the deleterious effect of eutectics. Fragmentation and dispersion of intermetallics, as well as intense grain refinement by dynamic recrystallization (DRX) were observed for the extruded composites due to the hot deformation effects, which resulted in the enhancement of the ultimate tensile strength, total elongation, and tensile toughness. Accordingly, it was concluded that Cu addition to Mg-Si composites should be limited to small amounts for modification effects, and if it is combined with the elevated-temperature thermomechanical processing, the optimum strength-ductility trade-off can be achieved.

Microstructure Evolution and Mechanical Properties of As-Cast and As-Compressed ZM6 Magnesium Alloys during the Two-Stage Aging Treatment Process.

In the present study, different solid solution and aging processes of as-cast and as-compressed ZM6 (Mg2.6Nd0.4Zn0.4Zr) alloy were designed, and the microstructure and precipitation strengthening mechanisms were discussed. After the pre-aging treatment, a large amount of G.P. zones formed in the α-Mg matrix over the course of the subsequent secondary G.P. prescription, where the fine and dispersed Mg12(Nd,Zn) phases were precipitated at the grain boundaries. The pre-aging and secondary aging processes resulted in the Mg12(Nd,Zn) phase becoming globular, preventing grain boundary sliding and decreasing grain boundary diffusion. Meanwhile, precipitation phase â″(Mg3Nd) demonstrated a coherent relationship with the α-Mg matrix after the pre-aging process, and after the secondary aging phase, Mg12Nd increases and became semi-coherent in the matrix. Compared to an as-cast ZM6 alloy, the yield strength of the as-compressed ZM6 alloy increased sharply due to an increase in the yield strength that was proportional to the particle spacing, where the dislocation bypassed the second phase particle. Compared to the single-stage aging process, the two-stage aging process greatly improved the mechanical properties of both the as-cast and as-compressed ZM6 alloys. The difference between the as-cast and as-compressed states is that an as-compressed ZM6 alloy with more dislocations and twins has more dispersed precipitates in the G.P. zones after secondary aging, meaning that it is greatly strengthened after the two-stage aging treatment process.

Modelling the tribological response in dry sliding of boron modified as-cast Ti6Al4V on hardened steel

Tribological characteristics of boron modified as-cast Ti6Al4V alloys are not very well known, but these alloys enjoy improved as-cast mechanical properties and favourable manufacturing economy. Experimental results are reported here for the effects of sliding speed and normal load on the wear rate and the coefficient of friction in dry sliding of these alloys on hardened EN 31 steel. Alloys having 0%, 0.30%, and 0.55% boron by weight were tested. A full factorial experiment assessed the effects of boron content, speed, and load on wear and friction. Interactions between speed and load were found to be statistically significant in influencing the wear rate and the coefficient of friction. Regression models are developed to predict the wear rate and coefficient of friction responses. The developed contour plots can assist designers in choosing operating conditions when selecting these alloys even if the wear mechanisms are unknown. Evidence shows that the wear resistance of Ti6Al4V can be improved by boron addition, and wear regimes are sensitive to boron content.

Enhanced mechanical properties of Mg–Ni–xRE alloys via hot extrusion

The effects of mischmetal addition and hot working on the enhancement of microstructure and mechanical properties of Mg–Ni alloys were studied. It was revealed that grain refinement could be achieved by introducing rare earth (RE) elements in the as-cast condition, and more pronouncedly, by the extrusion process in the wrought condition. While the formation of intergranular brittle phases via RE addition impaired the as-cast mechanical properties, the remarkable grain refinement and fragmentation and dispersion of intermetallic particles significantly improved the mechanical properties in the extruded condition. The ultimate tensile strength and total elongation of the extruded Mg–1.5Ni–3RE alloy with an average grain size of 3.18 μm (347 MPa and 9%) were much larger than those for the as-cast counterpart (140 MPa and 3%).

Microstructural evolution and mechanical properties of as-cast and annealed Nb–Si–Mo based hypoeutectic alloys with quaternary additions of Ti or Fe

The effect of quaternary addition of 20 at% Ti and 4 at% Fe on microstructural evolution, dynamically measured Young's modulus and Poisson's ratio, hardness, indentation fracture toughness (IFT), and compressive strengths of arc-melted hypoeutectic Nb–12Si–5Mo in as-cast or annealed (1500 °C for 100 h) condition have been investigated. Microstructural studies have shown the presence of primary niobium-rich solid solution (Nbss), and eutectic comprising Nbss+(β or α) (Nb, × )5Si3, where × = Mo, Ti, or Fe. Additionally, β-Tiss and Nb4FeSi have formed in Ti and Fe containing alloys, respectively. Annealing has led to conversion of partially lamellar to non-lamellar eutectic morphology, besides compositional alterations in phases. The dynamic Young's modulus being influenced by Mo-content of Nbss, and phase volume fractions, is found to peak in Ti-containg alloy (~150 GPa), with further increment on annealing (~162 GPa) due to β → α (Nb, × )5Si3 transformation. Whereas microhardness of Nbss (6–7 Hv) is influenced by solute content, that of eutectic (16–17 GPa) is also affected by (Nb, × )5Si3 content. Further, both hardness and compressive strength being influenced by phase volume fraction, and eutectic morphology, have decreased in Nb–12Si–5Mo and Nb–12Si–5Mo–20Ti alloys, but increased marginally in Nb–12Si–5Mo–4Fe alloy on annealing. The IFT appears to be the highest (~22 MPa√m) in the Ti-containing alloy, with toughening contributions from bridging and arrest of cracks by the ductile Nbss phase.

A Study of Effect of Vanadium on Microstructure and Mechanical Properties of As-Cast and Austempered Ductile Iron

The presence of vanadium, as an alloying element, has various effects on the properties of cast irons. In this research, the effects of adding different amounts of vanadium, including 0, 0.87, and 1.45 wt % V, on the microstructure, the formation of different phases, and the mechanical properties of the as-cast and austempered ductile iron have been investigated. After the casting of samples, preparation of the samples, and determining of their chemical composition, it is austenitization heat treatment at 900°C for 45 minutes and austempering heat treatment at 350°C for 60 minutes that were carried out on the samples. Tensile and impact tests, as well as X-ray diffraction (XRD) analysis and metallography, were conducted to study the mechanical properties and the structure. The microstructures of the samples included carbides in the ausferrite matrix. The results show that with increasing the vanadium, tensile strength and impact energy decrease in as-cast ductile iron, whereas heat treatment can improve them.

Thermal Conductivity and Mechanical Properties of As-Cast and As-Extruded Mg-Zn-Mn Alloys

As-cast and as-extruded Mg-[x]Zn-0.3Mn (x=1.5, 2.0 wt.%) alloys were prepared by means of medium-frequency induction-heating technique and extrusion process, respectively. The microstructural characteristics, thermal conductivity and mechanical properties of the samples were characterized. The research results show that the samples are composed of major α-Mg and minor second phases MgZn2. For the as-extruded samples, the grain size is refined. After extrusion, much more second phases were precipitated from α-Mg matrix and the dislocations were reduced. The degree of lattice distortion was decreased for as-extruded samples. Because of the decline of lattice distortion degree, the as-extruded samples display much higher thermal conductivity than the as-cast samples. Additionally, on account of lower lattice distortion, Mg-1.5Zn-0.3Mn alloy has a bit larger thermal conductivity than Mg-2Zn-0.3Mn alloy. Finally, the as-extruded alloys present good mechanical properties based on the fine-grained strengthening and second-phase strengthening mechanism.

A Comparative Study of Mechanical Properties Of As Cast And Heat Treated Al6063-MWCNT Composite Fabricated By Stir Casting Process

The Expansion of manufacturing industries has somewhere led to the increase in the use of composite materials. Metal Matrix Composites (MMC) are the advanced and new age materials that find application in sectors like automotive, aerospace, rail components, defense etc. because of their light weight, high strength, good corrosion, wear resistance and low thermal coefficient of expansion. Among the different methods of manufacturing MMCs, Stir casting process is one of the most important and economical method. The present work is about the preparation of aluminium Matrix Composite by stir casting technique, where Al 6063 is the matrix or the base metal and 2% by Weight of multiwalled carbon nanotubes (MWCNT) in powder form is the reinforcement material. Microstructure analysis will be done in order to observe the distribution of CNT particles in the Al matrix. The specimens will also be subjected to heat treatment before being tested. The ASTM standard specimens will then be tested for wear, tensile, compression, Impact and hardness to compare the results. The major objective of this work is to compare the mechanical properties of both As-cast and heat treated test samples for the aluminium 6063-MWCNT composite fabricated by means of stir casting process and hence compare the results.

The Effects of Grain Refinement and Rare Earth Intermetallics on Mechanical Properties of As-Cast and Wrought Magnesium Alloys

The effects of rare earth intermetallics and grain refinement by alloying and hot extrusion on the mechanical properties of Mg-Gd-Al-Zn alloys have been studied to elucidate some useful ways to enhance the mechanical properties of magnesium alloys. It was revealed that aluminum as an alloying element is a much better grain refining agent compared with gadolinium, but the simultaneous presence of Al and Gd can refine the as-cast grain size more efficiently. The presence of fine and widely dispersed rare earth intermetallics was found to be favorable to achieve finer recrystallized grains during hot deformation by extrusion. The presence of coarse dendritic structure in the GZ61 alloy, grain boundary eutectic containing Mg17Al12 phase in the AZ61 alloy, and rare earth intermetallics with unfavorable morphology in the Mg-4Gd-2Al-1Zn alloy was found to be detrimental to mechanical properties of the alloy in the as-cast condition. As a result, the microstructural refinement induced by hot extrusion process resulted in a significant enhancement in strength and ductility of the alloys. The presence of intermetallic compounds in the extruded Mg-4Gd-2Al-1Zn and Mg-2Gd-4Al-1Zn alloys deteriorated tensile properties, which was related to the fact that such intermetallic compounds act as stress risers and microvoid initiation sites.

Toward unraveling the effects of intermetallic compounds on the microstructure and mechanical properties of Mg–Gd–Al–Zn magnesium alloys in the as-cast, homogenized, and extruded conditions

The effects of gadolinium and aluminum intermetallics on the microstructure and mechanical properties of Mg-Gd-Al-Zn alloys in the as-cast, homogenized and extruded conditions were studied. It was revealed that the partial substitution of Gd with Al in the GZ61 alloy enhances the as-cast mechanical properties due to the evolution of intermetallic compound types, their morphology, and grain refinement of the matrix. In this regard, the best alloy was Mg-3Gd-3Al-1Zn due to the magnificent grain refinement from 1250 to 36µm as a result of the presence of the Al2Gd compound and there was respectively ~60% and 250% increase in tensile strength and elongation to failure when compared with the as-cast GZ61 alloy. Moreover, increasing Gd toward higher amount of (Mg, Al)3Gd phase with branched morphology impaired the mechanical properties. Subsequently, the homogenization heat treatment and extrusion process showed significant effects on the shape and size of intermetallics and grain size of the matrix. Regarding the extrusion process, the evolution of the (Mg, Al)3Gd compound in the Mg-4.8Gd-1.2Al-1Zn alloy combined with the recrystallization of the matrix resulted in the change in grain size from 670µm for the as-cast alloy to 2.4µm, which was found to be the key factor to enhance the properties and there was respectively ~34% and 135% increase in tensile strength and elongation to failure when compared with the as-cast alloy. However, it was also found that the microstructural refinement of hot extrusion process can effectively conceal the influences of intermetallic compound types and the chemical composition of the alloy on the tensile properties.

Low Cycle Mechanical and Fatigue Properties of AlZnMgCu Alloy

Abstract The article presents the analysis of properties of the high-strength AlZnMgCu (abbr AlZn) aluminium alloy and estimates possibilities of its application for responsible structures with reduced weight as an alternative to iron alloy castings. The aim of the conducted studies was to develop and select the best heat treatment regime for a 7xx casting alloy based on high-strength materials for plastic working from the 7xxx series. For analysis, wrought AlZnMgCu alloy (7075) was selected. Its potential of the estimated as-cast mechanical properties indicates a broad spectrum of possible applications for automotive parts and in the armaments industry. The resulting tensile and fatigue properties support the thesis adopted, while the design works further confirm these assumptions.

Development of high performance near eutectic Al–Si–Mg alloy profile by micro alloying with Ti

A high performance near eutectic Al–Si–Mg alloy profile is developed by micro alloying with 0.1wt.% Ti. The tensile properties of near eutectic Al–Si–Mg alloy with and without Ti in different processing conditions are tested for comparison. Microstructure evolution is observed by optical, scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). Results show that the yield strength (YS), ultimate tensile strength (UTS) and elongation of 0.1wt.% Ti alloyed A2 alloy reach up to 193 MPa, 296 MPa and 12.3% respectively, the tensile strength of which is about 50% higher than that of as-extruded base alloy and even stronger than that of the base alloy micro alloyed by 0.1wt.% Zr or 0.1wt.% V. Addition of 0.1wt.% Ti has obvious refine effect on the microstructure of as-cast Al–Si–Mg alloy, however, it has minor strengthening effect on the as-cast mechanical properties.

Recrystallization of a novel two-phase FeNiMnAlCr high entropy alloy

Cold rolling followed by annealing was performed on the as-cast, two-phase (f.c.c. + B2), lamellar-structured high entropy alloy Fe28.2Ni18.8Mn32.9Al14.1Cr6. The cold-rolled Fe28.2Ni18.8Mn32.9Al14.1Cr6 showed a very high yield strength of 1422 MPa due to the high dislocation density (>1 × 1015 m−2), but only 2.3% elongation to failure. Annealing produced recrystallization, which caused the as-cast lamellar microstructure to be replaced by an equi-axed, duplex grain structure consisting of discrete B2 and f.c.c. grains with both different compositions and volume fractions. The recrystallized alloy showed a yield strength of ∼600 MPa and an elongation of ∼20%, which was only slightly different from the as-cast mechanical properties, a feature ascribed to the similarity in the scale (0.5 μm) of the microstructure in the two states. It was found that although initial plastic deformation takes place in the f.c.c. phase, specimens either cold-rolled or strained to failure showed that both phases plastically deformed.