Influence of samarium on the microstructure and mechanical properties of Mg-Y-Zn-Zr alloys

Abstract

The effects of the Sm element on the microstructure of Mg-3Y-2Zn-0.6Zr (w/%) casting alloys were investigated, and the mechanical properties of the alloys were also tested at room temperature and different high temperatures of (423, 473, 523 and 573) K. Due to a heterogeneous nucleation, more refined grains were obtained with an increment of the Sm element. The precipitated phase at the grain boundaries changed from a discontinuous distribution to a continuous mesh. The main phase compositions were a-Mg, W phase-Mg3(Y, Sm)2Zn3 and X phase-Mg12(Y, Sm)Zn. The Y atoms were partly replaced by Sm in the secondary phase. The proportion of the substitutional solid solution increased and Sm-containing phases were not found in the alloy. With the increasing Sm amount, the tensile strength and yield strength increased slightly while the elongation decreased significantly at room temperature. However, the tensile strength at high temperatures decreased at first and then increased. As the temperature increased, the fracture of the MS alloys changed from the main intergranular fracture to a transgranular fracture.

Corrosion behaviour and properties of Mg–3.4Y–3.6Sm–2.6Zn–0.8Zr Alloy in 3.5 wt-% NaCl solution

“…Combined with EDS elemental analysis and XRD data, it can be determined that this phase is the Mg 12 (Y, Sm) Zn phase, this is similar to the study of Zhang and Hao [21,22]. According to our previous research [15], this stripe phase is also a kind of the LPSO phase.…”

“…The other is the light grey stripe phase (A4 area), this phase also distributed along the crystal with a long strip [21,22]. According to our previous research [15], this stripe phase is also a kind of the LPSO phase.…”

“…The raw materials include magnesium metal (purity 99.95wt-%), zinc metal (purity 99.98wt-%), Mg-30%Y, Mg-30%Zr and Mg-20%Sm master alloys. The Mg–3.4Y–3.6Sm–2.6Zn–0.8Zr alloy ingot was obtained by the self-researched smelting process [15]. The original microstructure of the ingot was confirmed by scanning electron microscopy (SEM, OXFORD), the actual composition of the as-cast experimental alloy was tested by X-ray fluorescence spectrometer (XRF, S8 TIGER) and the energy dispersive spectroscopy (EDS, TESCAN-VEGA-II-XMU) system was used to determine the local element distribution.…”

“…In our previous work, a new type of yttrium–samarium–magnesium alloy with good heat resistance has been designed and developed. The heat treatment process, fine grain strengthening [15,16] and new forming technology of the alloy [17,18] have been studied. However, its corrosion behaviour and performance are still unclear, it is essential to study the corrosion mechanism of alloy.…”

Research on the formation process of selective laser melting Mg–Y–Sm–Zn–Zr alloy

“…However, the mechanical properties of magnesium alloys are poor at high temperature, the strength and creep resistance decrease sharply when the temperature increases. The addition of mixed rare earth elements can improve the high temperature mechanical properties of the magnesium alloys [3]. In recent years, the development of new rare earth heat-resistant magnesium alloys is one of the important topics.…”