Effects of Different Rare Earth Elements on the Degradation and Mechanical Properties of the ECAP Extruded Mg Alloys

Effects of different rare earth elements on the degradation and mechanical properties of the ECAP (equal channel angular pressing) extruded Mg alloys were investigated in this work. Microstructural characterization, thermodynamic calculation, a tensile test, an electrochemical test, an immersion test, a hydrogen evolution test and a cytotoxicity test were carried out. The results showed that yttrium addition was beneficial to the improvement of the alloy’s strength, and the ultimate tensile strength (UTS) and yield strength (YS) values of the ECAPed Mg-2Zn-0.5Y-0.5Zr alloy reached 315 MPa and 295 MPa, respectively. In addition, Nd was beneficial to the corrosion resistance, for which, the corrosion rate of the ECAPed Mg-2Zn-0.5Nd-0.5Zr alloy was observed to be 0.42 ± 0.04 mm/year in Hank’s solution after 14 days of immersion. Gd was moderate in improving both the corrosion resistance and mechanical properties. Moreover, after co-culturing with murine calvarial preosteoblasts (MC3T3-E1) cells, the ECAPed Mg-2Zn-0.5RE (Nd, Gd, Y)-0.5Zr alloys exhibited good cytocompatibility with a grade 1 cytotoxicity. Consequently, the ECAPed Mg-2Zn-0.5Nd-0.5Zr alloy showed the best application prospect in the field of orthopedics.

Effect of Heat Treatment on Microstructure and Dimensional Stability of Y-Modified AlSi7Cu3Mg Alloy

The application of rare earth modified AlSi7Cu3Mg alloy in automobile engine and motor casing has increased. The dimensional stability of this alloy is an important feature. In this paper, the effects of yttrium addition and different heat treatment on the microstructure and dimensional thermal stability of AlSi7Cu3Mg alloy were studied by OM, SEM and dimensional measurement. Research shows that: The dimensional stability of AiSi7Cu3Mg alloy after T6 heat treatment is better than that after T4 heat treatment, and the dimensional stability after T7 heat treatment is the best. The addition of rare earth Y can improve the dimensional stability of AiSi7Cu3Mg alloy.

Effect of Yttrium Addition on Structure and Magnetic Properties of Co60Fe20Y20 Thin Films

In this paper, a Co60Fe20Y20 film was sputtered onto Si (100) substrates with thicknesses ranging from 10 to 50 nm under four conditions to investigate the structure, magnetic properties, and surface energy. Under four conditions, the crystal structure of the CoFeY films was found to be amorphous by an X-ray diffraction analyzer (XRD), suggesting that yttrium (Y) added into CoFe films and can be refined in grain size and insufficient annealing temperatures do not induce enough thermal driving force to support grain growth. The saturation magnetization (MS) and low-frequency alternate-current magnetic susceptibility (χac) increased with the increase of the thicknesses and annealing temperatures, indicating the thickness effect and Y can be refined grain size and improved ferromagnetic spin exchange coupling. The highest Ms and χac values of the Co60Fe20Y20 films were 883 emu/cm3 and 0.26 when the annealed temperature was 300 °C and the thickness was 50 nm. The optimal resonance frequency (fres) was 50 Hz with the maximum χac value, indicating it could be used at a low frequency range. Moreover, the surface energy increased with the increase of the thickness and annealing temperature. The maximum surface energy of the annealed 300 °C film was 30.02 mJ/mm2 at 50 nm. Based on the magnetic and surface energy results, the optimal thickness was 50 nm annealed at 300 °C, which has the highest Ms, χac, and a strong adhesion, which can be as a free or pinned layer that could be combined with the magnetic tunneling layer and applied in magnetic fields.

The Effect of Yttrium Addition on the Microstructure and Irradiation Hardening in V-4Cr-4Ti Alloy under Self-Ion Irradiation

Microstructure and irradiation hardening of V-4Cr-4Ti alloys with different yttrium (Y) contents were studied by self-ion irradiation at 550 °C via TEM and nano-indentation test technology. The peak damage of the V-4Cr-4Ti-xY alloy (x = 0, 0.1, 0.5, and 1, wt.%) irradiated by 2.5 MeV self-ion (V2+) is 8 dpa. Dense dislocation loops were observed in all vanadium alloy samples after irradiation. With the increase of Y content, both average size and number density of dislocation loops using g = <110> near the pole [001] decreased, while the irradiation hardness increment first decreased and then increased. In order to better reduce the irradiation hardening, it is considered that the addition of 0.1 wt.% Y in V-4Cr-4Ti alloy is reasonable.

Effects of Yttrium Addition on the Microstructure Evolution and Electrochemical Corrosion of SN-9zn Lead-Free Solders Al-Loy

Electrochemical corrosion behavior of ternary tin-zinc-yttrium (Sn-9Zn-xY) solder alloys were investigated in aerated 3.5 wt.% NaCl solution using potentiodynamic polarization techniques, and the microstructure evolution was obtained by scanning electron microscope (SEM). Eight different compositions of Sn-9Zn-xY (x = 0, 0.02, 0.04, 0.06, 0.08, 0.10, 0.20, and 0.30 wt.%) were compared by melting. The experimental results show that when the content of Y reached 0.06 wt.%, the grain size of Zn-rich phase became the smallest and the effect of grain refinement was the best, but there was no significant effect on the melting point. With the increases of Y content, the spreading ratio first increased and then decreased. When the content of Y was 0.06 wt.%, the Sn-9Zn-0.06Y solder alloy had the best wettability on the Cu substrate, which was increased by approximately 20% compared with Sn-9Zn. Besides, the electrochemical corrosion experimental shows that the Y can improve the corrosion resistance of Sn-9Zn system in 3.5 wt.% NaCl solution, and the corrosion resistance of the alloy is better when the amount of Y added is larger within 0.02–0.30 wt.%. Overall considering all performances, the optimal performance can be obtained when the addition amount of Y is 0.06.