The influence of yttrium on the microstructure and corrosion behaviour of as-cast Mg–8Li–3Al–2Zn–xY alloys was investigated. The results show that Y addition leads to the formation of Al₂Y particles and the transformation of α-Mg from the long needle-like to the round-like. The noble Al₂Y particles on the grain boundary inhibit the galvanic corrosion between β-Li phase and α-Mg phase, and also weaken the corrosion occurrence inside β-Li phase due to the decrease of the AlLi phase. With Y addition, the corrosion resistance is improved gradually, especially when the content of Y is up to 1.5 wt-%. Moreover, Y addition makes the corrosion film become more compact, which can prevent the base materials from being attacked continuously.

The corrosion behaviors of low-pressure sand cast Mg-10Gd-3Y-0.5Zr (wt.%) alloys in as-cast, solution treated (T4) and aged (T6) conditions were studied by means of immersion test and electrochemical measurements in 5wt.% NaCl solution saturated with Mg(OH)₂. It was observed that the corrosion rate in the T4 condition was lower than that of the as-cast and T6 conditions by both sand casting and permanent mold casting with the same order of as-cast>T6>T4; while the corrosion resistance of the permanent mold casting is superior to the sand casting. The morphologies of the corrosion products are similar porous structures consisting of tiny erect flakes perpendicular to the corroded surface of the alloy, irrespective of the heat treatment conditions. Especially, the corrosion film in T4 condition is more compact than that in the other two conditions. In addition, the severer corrosion happening to the as-cast condition is correlated with the galvanic corrosion between the matrix and the eutectic compounds; while improved corrosion resistance for the T4 and T6 conditions is ascribed to the dissolution of the secondary eutectic compounds. The measured corrosion current densities of Mg-10Gd-3Y-0.5Zr alloys in as-cast, T4, and T6 conditions are 36 μA·cm^-2, 10 μA·cm^-2, and 33 μA·cm^-2, respectively. The proposed equivalent circuit [R_s(CPE₁(R_t(R_fCPE₂))] by Zview software matches well with the tested electrochemical impedance spectra (EIS) data.

The widespread application of WE43 (Mg-4Y-2Nd-1Gd-0.5Zr) alloy castings in aerospace components is hindered by the frequent formation of defects such as cracks, pores, and especially yttria inclusions. These defects necessitate subsequent welding. However, using homologous WE43 filler wires often exacerbates these issues, leading to high crack susceptibility and reintroduction of inclusions. Herein, we propose a novel strategy of tailoring Y content in filler wires to achieve high-quality welded joint of WE43 sand castings. Systematic investigations reveal that reducing Y content to 2 wt.% (WE23) effectively suppresses oxide inclusion formation and significantly enhances the integrity of the joint. The fusion zone microstructure evolves distinctly with varying Y levels: grain size initially increases, peaking at 24 μm with WE43 wire, then decreases with further Y addition. Moreover, eutectic compounds transition from a semi-continuous to a continuous network structure with increasing Y content, deteriorating mechanical performance. Notably, joints welded with WE23 filler exhibit minimal performance loss, with ultimate tensile strength, yield strength, and elongation reaching 93.0%, 98.0%, and 97.4% of the sand-cast base metal, respectively. The underlying strengthening mechanisms and solute-second phase relationships are elucidated, highlighting the efficacy of optimizing Y content in welding wire design. This study provides valuable insights toward defect-free welding of high-performance Mg-RE alloy castings.

Effects of seven antihypertensives of Losartan Kalicum(LK), Atenolol(ATEN), Nifedipine(NF), Hydrochlorothiazide(HCTZ), Valsartan(VLA), Furosemide(FUR) and Captopril(CAP) have been investigated on the degradation behavior of AZ31 alloy in simulated body fluid (Hank's solution). LK, NF and HCTZ with the concentrations of 0.5, 1.0 and 0.5 g/L can remarkably enhance the degradation resistance of AZ31 alloy by 63.1, 69.4 and 70.5%, respectively. The surface analysis reveals that the addition of LK, NF and HCTZ can reduce degradation rate by promoting the growth of hydroxyapatite, increasing the protection effect of corrosion film formed. The present results may enhance the corrosion resistance of Mg-based orthopedic implants.