Mechanical Properties Of As-cast Alloy Research Articles

Microstructure and High-Temperature Mechanical Properties of Mg-1Al-12Y Alloy Containing LPSO Phase

This paper describes our study on the effect of the long-period stacking order (LPSO) phase on the comprehensive mechanical properties of the as-cast Mg-1Al-12Y (wt. %) alloy. The microstructure and tensile mechanical properties of as-cast alloy and solution treatment alloy were evaluated. The results showed that α-Mg matrix, Al2Y phase and β-Mg24Y5 phase were present in the as-cast alloy. After solution treatment, the β-Mg24Y5 phase in the alloy was dissolved and the LPSO phase was precipitated. The solution treatment did not cause grain growth or Al2Y phase change, but the comprehensive mechanical properties of the alloy were significantly improved. This was mainly due to the precipitation of the LPSO phase in the solid solution alloy. In addition, the dissolution of the β-Mg24Y5 phase after solution treatment could also improve the mechanical properties. The improvement of the comprehensive mechanical properties of solution treatment alloys at room temperature was due to the dispersion strengthening caused by the intragranular LPSO phase dispersed within the alloy, which had a good blocking effect on the movement of dislocations. The ductility of the solid-solution alloy was greatly improved at a high temperature while maintaining high strength because the LPSO phase is kinked, the dislocation density was reduced, and more non-basal slip was activated during the high-temperature tension.

Microstructure and mechanical properties of as-cast Mg–Nd–Zn–Y–Zr alloys

Mg-2.4Nd-0.2Zn-0.5Zr-xY (x=0, 0.6, 1.2, 1.8wt.%) alloys were fabricated by a casting method, the microstructure and mechanical properties of as-cast alloys were investigated. The results demonstrate that the A, B, C and D alloys are composed mainly of α-Mg and Mg12Nd phases. Phases containing Y were not formed, because trace amounts of Y element was completely dissolved into Mg matrix. The addition of Y was found to improve the mechanical properties of the alloys. The Mg-2.4Nd-0.2Zn-0.4Zr-1.8Y alloy exhibits the optimal mechanical properties in the as-cast condition, the maximum value of ultimate tensile strength, yield strength and elongation to failure were 192MPa, 168MPa and6.5%, respectively.

A novel NbTaW0.5 (Mo2C)x refractory high-entropy alloy with excellent mechanical properties

In this study, a refractory high-entropy alloy (RHEA) NbTaW0.5 was selected as the master alloy and carbide Mo2C was added to prepare the NbTaW0.5(Mo2C)x (x = 0–0.25) RHEAs. The effect of Mo2C addition on the phase composition, microstructure evolution, and mechanical properties of the as-cast and annealed RHEA was investigated. The microstructure and mechanical properties of the as-cast and isothermally annealed (1673 K/12 h) NbTaW0.5(Mo2C)x RHEAs were studied. The results showed that the as-cast RHEAs consisted of a disordered body-centered cubic solid solution phase and a second M2C carbide phase with hexagonal close-packed (HCP) crystal structure. The HCP–M2C carbides were enriched with Nb, Ta, and C elements and tended to achieve a similar eutectic morphology in the interdendritic regions. After isothermal annealing, orthorhombic carbides were formed near the primary carbides, which apparently depleted the carbon supersaturation of the matrix. The compression mechanical properties of as-cast alloys were determined at room temperature, 1473 K, and 1673 K. The yield strength of NbTaW0.5(Mo2C)0.2 RHEA exceeded 1000 MPa at 1473 K, and even reached 697 MPa at 1673 K, far exceeding some of the currently reported RHEAs. These RHEAs had good plasticity and showed excellent application prospects.

The structure of AlFe5 master alloys produced from recyclable scrap steel and its effect on the properties of aluminium alloys

Due to growing production of aluminium alloys and development of resourcesaving production, great amounts of waste products are widely used in the production process. Use of recyclable iron-containing waste in cast and wrought aluminium alloy production diverts the common traditional understanding that iron can affect the cast structure. At the same time, for the low diffusion capacity of iron in aluminium, it would be interesting to consider Al – Fe alloys. This paper describes the results of a study that examined how the structure of AlFe5 master alloys influence the structure and properties of Al – Si – Cu (AK12M2) and Al – Cu – Mg (AK4) alloys. The test AlFe5 master alloys were prepared by chopping waste steel wire into 1 and 3 mm pieces. The alloy melts solidified in a crucible and a water-cooled roller mould. Before pouring, some of the alloy melts were exposed to electromagnetic acoustic fields for additional conditioning. The authors looked at how the size of the steel pieces and the way they were obtained changed the structure of the test master alloys. A relationship was established between the size of the material and the dimensions and quantity of FeAl3 intermetallics. In all experiments, the bigger FeAl3 intermetallics were found in alloys produced with 3 mm steel pieces. Exposure to electromagnetic acoustic fields would result in 3–5 times smaller FeAl3 intermetallics while their quantity would increase by 4–10 times. The chemical compositions of alloys obtained from fine-crystalline master alloys proved to be in compliance with applicable regulations. The principal phases in the resultant alloys had a fine-dispersed structure. The eutectic silicon in the АК12М2 alloy became 1.4 times smaller, while the dendritic aluminium in the АК4 alloy structure became 1.65 times smaller. The optimized structure led to improved physical and mechanical properties of as-cast alloys. Thus, their ultimate strength increased by 10–13%, while their specific elongation almost doubled. The results of the study indicate that recyclable scrap steel wire can be effectively used in the production of aluminium alloys.This research study was funded by the Ministry of Education and Science of Russia as part of a governmental assignment; Project ID: 0718-2020-0030.

Mechanical Properties of Stoichiometrically Developed Al-Cu-Mg Cast Alloy Under Controlled Environment

Present study was carried out to investigate the mechanical properties of newly developed cast aluminum alloy with addition of (1.0 aged heat treatment, AHT %) of copper and (1.0 AHT %) magnesium in the mole ratio of 1:1:1 Al-Cu-Mg in as-cast and thermally aged conditions. The (AHT %) selection of Cu-Mg on the basis of stoichiometric calculations, 1 unit (AHT %) of copper and 1 unit (AHT %) of magnesium were mixed in liquid aluminium base material, heated in an electric furnace and melt was hold at 730 ºC with alloying additions of copper and magnesium for about 30 min to ensure complete homogenisation, Further, this liquidous aluminium metal matrix was stirred at 800 rpm for 5 min and poured at 700 ± 10 ºC in permanent mild steel mould pre-heated at 200 ºC in order to achieve as-cast alloy. Solution treatment at 500 ºC for 1 h and thermally aged at temperature 160 ºC for 5 h was exposed. The effect of solution and aged temperature on metallurgical morphology and further the role of intermetallic compounds on mechanical properties of as-cast alloy have been studied. The optical microscopy and scanning electron microscopy equipped with energy dispersive spectroscopy were used to identify the intermetallic phases and formation of different precipitates was studied by using X-ray diffraction. The improvement in ultimate tensile strength and hardness values have been reported.

Effects of pressure and aging treatment on microstructures and mechanical properties of rheo-squeeze casting Mg–3Nd–0.2Zn–0.4Zr alloy

Abstract

Microstructure and mechanical properties of Mg–9RY–4Cu alloy with long period stacking ordered phase

The microstructure and mechanical properties of Mg–9RY (RY: Y-rich misch metal)–4Cu (wt%) alloys have been investigated. In as-cast state, the LPSO phase presents lamellar structure at grain boundaries or in the interdendritic regions and fine lamellae in Mg grains. After hot extrusion, the LPSO phase presents bent long-strip-shape distributed along the extrusion direction. The as-cast and as-extruded alloys exhibit excellent compression properties and strong work hardening responses. The high mechanical properties of as-cast alloy are mainly attributed to the hard LPSO skeleton and high-density LPSO lamellae. In as-extruded state, besides the hard LPSO phase itself serve as a strengthening phase, multiple strengthen mechanism contributes to the high mechanical properties, including the well aligned long-strip-shape morphology of LPSO phase, kinked LPSO phase and fine dynamic recrystallized (DRX) grains with fine lamellae phase. The kinking of the LPSO phase during plastic deformation is beneficial to the obvious work hardening for both as-cast and as-extruded alloys.

Defects in Mg-Zn-Y-Nd Alloys with Icosahedral Phase

Abstract Recently it was reported that icosahedral phase (I-phase) with quasicrystalline structure is formed in some lightweight Mg alloys. It was found that Mg alloys containing I-phase exhibit improved mechanical properties which make them attractive for industrial applications. This work presents microstructure investigations and defect studies of squeeze cast Mg-Y-Nd-Zr (WE43) alloy with addition of 14 wt.% and 26 wt.% Zn. For comparison WE43 alloy without any Zn was investigated as well. Presence of the quasicrystalline I-phase was detected by electron diffraction and X-ray diffraction in both WE43 alloys modified by Zn addition. On the other hand, WE43 without Zn does not contain any I-phase. Mechanical properties of as-cast alloys were examined by Vickers microhardness (HV) testing. It was found that presence of I-phase leads to a significant hardening. Defects in as-cast alloys were investigated by positron lifetime (LT) spectroscopy combined with coincidence Doppler broadening (CDB). Reference sample WE43 alloy without Zn exhibits a single-component LT spectrum with lifetime of ∼ 224 ps which is close to the Mg bulk lifetime. On the other hand, vacancy-like defects characterized by positron lifetime of ∼ 300 ps were found in WE43 alloys modified by Zn addition. CDB investigations revealed that chemical environment of these defects is enriched with Zn and Y. Hence, our results indicate the existence of vacancy-like defects connected with the I-phase. We suggest that these defects are located at the interfaces between the I-phase and the Mg-matrix.

The Microstructure and Mechanical Properties of Mg-8Zn-8Al-4RE Magnesium Alloy

The Mg-8Zn-8Al-4RE (RE = mischmetal, mass%) magnesium alloy was prepared by using casting method. The microstructure and mechanical properties of as-cast alloy, solid solution alloy and aged alloy samples have been investigated. Optical microscopy, X-ray diffractometery and scanning electron microscope attached energy spectrometer were used to characterize the microstructure and phase composition for the alloy. Net shaped τ-Mg32(Al,Zn)49 phase was obtained at the grain boundary, and needle-like or blocky Al11RE3 phase disperses in grain boundary and α-Mg matrix. The τ-Mg32(Al,Zn)49 phase disappeared during solution treatment and a new phase of Al2CeZn2 formed during subsequent age treatment. The mechanical properties were performed by universal testing machine at room temperature, 150 °C and 200 °C, separately. The ultimate tensile strength of as-cast alloy is lower compared to an age treatment alloy at 200 °C for 12h. The strengths decreased with enhancing test temperature, but elongation has not been effect by age treatment.

Influence of Zirconium on Phase Composition, Structure, and Mechanical Properties of As-Cast Alloys of Ti-Al-Si System

Article Influence of Zirconium on Phase Composition, Structure, and Mechanical Properties of As-Cast Alloys of Ti-Al-Si System was published on April 1, 2006 in the journal High Temperature Materials and Processes (volume 25, issue 1-2).