Al2Sm Phase Research Articles

Effect of samarium (Sm) addition on microstructure and mechanical properties of Al-5Cu alloys

The purpose of this study is to investigate the influence of samarium addition on the microstructures and mechanical properties of Al-5Cu alloys. The microstructures were examined by optical microscopy, X-ray diffraction, scanning electron microscopy, energy diffraction spectroscopy and differential thermal analysis. It was found that Sm was capable significantly of affecting the microstructures of Al-5Cu alloys. When 0.4 wt% Sm was added into the alloy, the aspect ratio and the mean area of Al2Cu phase were 10.9 and 61.0 μm2. They were decreased by 31.5% and 43.3% when compared with unmodified alloy. Meanwhile, a kind of nano size strengthening Al2Sm phase was formed in Al-5Cu alloys. In addition, the differential thermal analysis results showed that Sm addition results in a decrease in the melting temperature of α-Al and Al2Cu. And a good combination of yield strength (244.5 MPa), ultimate tensile strength (269.4 MPa) and elongation (6.9%) was obtained when the Sm addition was 0.4 wt%. Compared with unmodified Al-5Cu alloys, they were increased by 37.6%, 35.2% and 21.1%, respectively.

Effects of ultrasonic vibration on microstructure evolution and elevated-temperature mechanical properties of hot-extruded Mg-6Al-0.8Zn-2.0Sm wrought magnesium alloys

The effects of ultrasonic vibration on microstructure evolution and elevated-temperature mechanical properties of hot-extruded Mg-6Al-0.8Zn-2.0Sm wrought magnesium alloys have been investigated. The results show that morphology of relatively coarser Al2Sm phases in the alloy exhibit petal-shaped. However, after being treated by ultrasonic vibration, the Al2Sm phase morphology changes to fine particles. The ultimate tensile strength of the ultrasonic treated Mg-6Al-0.8Zn-2.0Sm alloy at 150 °C has a highest value of 298 MPa and elongation of 20.8%. The maximum pressure caused by transient cavitation is far greater than the shear strength of the Al2Sm phase, which makes the coarse petal-shaped Al2Sm phase break apart into fine polygon particles. Acoustic streaming than makes the broken polygonal Al2Sm particles smooth and uniformly disperse.

Effects of calcium, samarium addition on microstructure and mechanical properties of AZ61 magnesium alloy

The microstructure and mechanical properties of AZ61 magnesium alloy with Ca, Sm addition were investigated. The results showed that the addition of 0.5 wt.% Ca reduced the quantity of Mg17Al12 phase, and formed a new Al4Ca phase which is reticular in AZ61 alloy. With the addition of Ca and Sm, the microstructure was further refined and new Al-Sm rich phases were formed in AZ61 alloy with 0.6 wt.%–1.5 wt.% Sm addition, the TEM analysis confirmed that they were Al2Sm and Al4Sm. Tensile tests showed that 1.0 wt.% Sm addition contributed to the formation of the Al2Sm and Al4Sm and the improvement in the ambient strength, i.e., an ultimate tensile strength of 327 MPa and an elongation of 10.1%. However, excessive Sm addition led to the coarsening of Al2Sm and Al4Sm phases, thus resulted in the decline of strength and plasticity.

Microstructures and mechanical properties of Mg–Al–Sm series heat-resistant magnesium alloys

The microstructures and phase compositions of the as-cast and die-cast Mg–6.02Al–1.03Sm, Mg–6.05Al–0.98Sm–0.56Bi and Mg–5.95Al–1.01Sm–0.57Zn alloys were investigated. Meanwhile, the tensile mechanical and flow properties were tested. The results show that the as-cast microstructure of Mg–6.02Al–1.03Sm alloy is composed of α-Mg matrix, discontinuous β-Mg17Al12 phase and small block Al2Sm phase with high thermal stability. Rod Mg3Bi2 phase precipitates when Bi is added, while the added metal Zn dissolves into α-Mg matrix and β-Mg17Al12 phase. The as-cast alloys exhibit the excellent tensile mechanical property. The tensile strength (σb) and elongation (Δ) can reach 205–235 MPa and 8.5%–16.0% at ambient temperature, respectively. Meanwhile, they can also exceed 160 MPa and 14.0% at 423 K, respectively. The die-cast microstructures are refined obviously, and meanwhile the broken second phases distribute dispersedly. The die-cast alloys exhibit better tensile mechanical properties with the values of σb and Δ of 240–285 MPa and 8.5%–16.5% at ambient temperature, respectively, and excellent flow property with the flow length of 1870–2420 mm. The die-cast tensile fractures at ambient temperature exhibit a typical character of ductile fracture.

Grain Refinement Strengthening of Sm in AZ61 Alloy

The grain refinement and relative strengthening of rare earth element Sm in magnesium alloy AZ61 has been investigated. The results show that high melting point Al2Sm phase forms in AZ61 alloy with the addition of 2wt.% Sm. It leads to the refinement of grain size and enhances the strength of AZ61 alloy.

Effect of samarium on microstructure and corrosion resistance of aged as-cast AZ92 magnesium alloy

The effects of samarium (Sm) on microstructure and corrosion resistance of AZ92 magnesium alloy were characterized and analyzed by scanning electronic microscopy, X-ray diffraction, mass loss test, electrochemical impedance spectroscopy, X-ray photoelectron spectroscopy and potentio-dynamic polarization test. The results showed that the added Sm could promote continuous precipitation of β-Mg17Al12 phase in grains, and meanwhile restrain discontinuous precipitation of the same phase along the grain boundaries. Thus, the precipitations distributed more uniformly in the aged AZ92 magnesium alloys. When the content of Sm was 0.5 wt.%, the corrosion resistance of aged AZ92 alloy tended to be the best, which was due to the β-phase distributes more homogeneous reducing the galvanic corrosion. The corrosion product film had more integrality and compactness than AZ92 alloys without Sm. However, it resulted in worse corrosion resistance of AZ92 alloy because of the formation of mass cathodic Al2Sm phase coming from excess Sm in AZ92 alloy.

Effects of Sm addition on microstructure and mechanical properties of Mg–6Al–0.6Zn alloy

The microstructures and mechanical properties of Mg–6Al–0.6Zn alloy with Sm addition have been investigated. The results show that Sm can dramatically improve the yield strength and tensile strength of the alloy at 20–175 °C. With 0.5–2.0 wt.% Sm addition, the microstructure of alloy is remarkably refined. Spotted, high-melting point Al2Sm phases are found in the alloy. The microstructure and mechanical properties of the alloy with 1.5 wt.% Sm addition are found to be optimum.