Gd Zr Research Articles

Mechanisms of Magnetic Hysteresis in Heterogeneous Gd‒Zr‒Co‒Cu‒Fe Alloys

Mechanisms of Magnetic Hysteresis in Heterogeneous Gd‒Zr‒Co‒Cu‒Fe Alloys

Effect of Samarium on the Properties of Hot-Extruded Mg–Y–Gd–Zr Alloys

The effect of such an additional promising alloying element as samarium on hot-extruded Mg–Y–Gd–Zr alloys is investigated. The microstructure, kinetics of aging during the decomposition of a supersaturated Mg solid solution, and the mechanical properties of the alloys are studied. The differences of the recrystallization processes that occur in hot-extruded alloys with various contents of samarium (0, 1.7, 2.5%) are demonstrated. After hot extrusion, Mg–Y–Gd–Zr and Mg–Y–Gd–Sm–Zr alloys are additionally hardened during aging due to the decomposition of a supersaturated Mg solid solution. At the same time, samarium changes the nature of this hardening. The alloys with samarium are hardened faster, and the maximum hardness is achieved with shorter aging exposures. The mechanical properties of hot-extruded Mg–Y–Gd–Zr alloys with samarium addition are determined at room and elevated up to 300 °C temperatures. The efficiency and expediency of using samarium both as a separate alloying element and as a partial replacement of more expensive rare-earth elements in alloys with yttrium and gadolinium are shown.

A comparative study of deformation behaviors and ductility improvement in Mg–Gd–Zr and Mg–Zr cast alloys

This study investigates the impact of Gd elements on the enhancement of ductility in the Mg–Gd–Zr alloy. The deformation behavior at room temperature of the cast Mg–Gd–Zr alloy and the cast Mg–Zr alloy was examined using the EBSD-assisted slip trace method. The quantitative analysis of the initiation ratio of each slip system in the two alloys revealed that the Mg–Gd–Zr alloy had a higher ratio of non-basal slip systems. The experimental determination of the critical resolved shear stress (CRSS) ratios of non-basal slip to basal slip for both alloys indicated that the Gd elements could reduce this ratio, facilitating the initiation of more non-basal slip systems to accommodate strain. Furthermore, the segregation of Gd elements at grain boundaries was observed to enhance the grain boundary strength of the alloy, which is a significant factor in the enhancement of ductility.

Compressive creep behavior and microstructural evolution of sand-cast and peak-aged Mg–12Gd–0.4Zr alloy at 250 °C

Magnesium (Mg) alloys with high concentrations of Gd additions are known to exhibit high strength and good creep resistance at elevated temperatures. However, the main mechanisms including microstructural evolution and dislocation configurations for clarifying the low creep rates of Mg–Gd–Zr alloys are still controversial. The present work investigates the compressive creep behavior of both the sand-cast and peak-aged Mg–12Gd–0.4Zr (wt.%) alloys at a fixed temperature of 250 °C under the applied stress range of 60–100 and 80–120 MPa, respectively. It is revealed that β' and β'F precipitates distribute alternately forming precipitate chains in Mg–Gd–Zr alloys. Furthermore, β'+β'F precipitate chains led to the honeycomb-like structure in the sand-cast alloy during the creep process, improving its creep resistance to some extent. Nevertheless, weakly strengthening β1 precipitates occurred and detrimental β phases coarsened, which weakened the creep performance of the sand-cast alloy. However, the slight improvement of creep resistance in the peak-aged Mg–12Gd–0.4Zr alloy can be mainly attributed to the formation of precipitate-free zones (PFZs) and also the premature coarsening of β'+β'F precipitate chains. During creep, the cross slip of basal and prismatic <a> dislocations become the dominant creep mechanism for the sand-cast alloys. By contrast, the cross-slip of basal <a> dislocations and pyramidal <c + a> dislocations is the dominant creep mechanism for the peak-aged alloys, which was arrested by precipitates then strengthening the creep resistance of peak-aged alloys.

Purification of Mg–Gd–Zr Alloys With Pulsed Electric Current

Purification of Mg–Gd–Zr Alloys With Pulsed Electric Current

Improvement of dynamic compression properties and strengthening mechanism of Mg–Y–Nd–Gd–Zr alloy by pre-twinning

Improvement of dynamic compression properties and strengthening mechanism of Mg–Y–Nd–Gd–Zr alloy by pre-twinning

Properties of a Light Structural Magnesium IMV7-1 Type Alloy of the Mg–Y–Gd–Zr System with the Additions of Cerium-Group Rare-Earth Metals Such as Samarium, Neodymium, and Lanthanum

Properties of a Light Structural Magnesium IMV7-1 Type Alloy of the Mg–Y–Gd–Zr System with the Additions of Cerium-Group Rare-Earth Metals Such as Samarium, Neodymium, and Lanthanum

Effect of Rotary Swaging on the Structure and Properties of Mg–Y–Gd–Zr Magnesium Alloys

Effect of Rotary Swaging on the Structure and Properties of Mg–Y–Gd–Zr Magnesium Alloys

Effect of Sm on microstructures and mechanical properties of Mg–Gd(–Sm)–Zr alloys by hot extrusion and aging treatment

We investigated the effect of Sm on microstructures and mechanical properties of Mg–Gd (–Sm)–Zr by hot extrusion and aging treatment. The dynamic recrystallization (DRX) and precipitation behavior were analyzed by the electron backscattering diffraction (EBSD) and transmission electron microscope (TEM). For as-extruded alloys, the addition of Sm promotes DRX and dynamic precipitation, and the dynamic precipitation can activate the particle-stimulated nucleation (PSN) mechanism to promote the nucleation of DRX. The DRX grains of the as-extruded Mg–Gd–Zr show a random texture, but the as-extruded Mg–Gd–Sm–Zr shows an abnormal texture (<0001>Mg was parallel to the extrusion direction). For the extruded-aged alloys, the matrix precipitates of the Mg–Gd–Zr and Mg–Gd–Sm–Zr were all β′. But the size of β′ in Mg–Gd–Sm–Zr was smaller. The grain boundaries precipitates of the two alloys were all β. The β phase of Mg–Gd–Zr was granular and distributed discontinuously, while that of Mg–Gd–Sm–Zr was continuous distribution. Furthermore, there was an obvious precipitation-free zone of extruded-aged Mg–Gd–Sm–Zr. The high-temperature mechanical properties of extruded-aged Mg–Gd–Sm–Zr were obviously improved by the addition of Sm. The tensile strength, yield strength and elongation at 200 °C were 336 MPa, 271 MPa and 7.4%, respectively. Finally, the strengthening mechanism of extruded-aged Mg–Gd–Sm–Zr was analyzed in detail.

Effect of stacking faults in nanograins on the tensile properties of Mg–Y–Nd–Gd–Zr alloys subjected to ultrasonic surface rolling processing

In this study, an Mg–Y–Nd–Gd–Zr alloy was subjected to ultrasonic surface rolling processing (USRP), and a deformation layer approximately 651 μm deep was observed. It shows a double-gradient microstructure as the grain size increased and the twin density decreased. The grain size at the top surface layer was refined to 147.08 nm, and several stacking faults (SFs) were observed in the nanograins. Two main types of SFs were observed, including intrinsic I1 SFs bounded by 1/6〈202¯3〉 Frank partial dislocations and intrinsic I2 SFs bounded by 1/3〈101¯0〉 Shockley partial dislocations. The SFs induced a strong hindrance to dislocation motion, improving the yield strength of the alloy. Also, the dislocation caused by SFs increased the stress concentration of the nanograins and promoted premature fracture failure at the top surface of the alloy, reducing its plasticity after USRP. In addition, the tensile fracture of the alloy changed from plastic fracture mechanism dominated by micropore aggregation before USRP to brittle fracture mechanism dominated by cleavage planes and steps after USRP.

Effect of Samarium on the Strength Properties of Mg–Y–Gd–Zr Alloys

Effect of Samarium on the Strength Properties of Mg–Y–Gd–Zr Alloys

Effects of content and distribution of Zn and Gd on formation ability of I phase and W phase in Mg‒Zn‒Gd‒Zr alloy

The solid solution and compounds in Mg‒Zn‒Gd‒Zr magnesium alloy semicontinuous casting ingots were effectively separated by phase separation technique，the solid solution quantity of Zn and Gd as well as the mass ratio of Mg3GdZn6 (I phase) and Mg3Gd2Zn (W phase) compounds were determined, and the mass fraction of I phase and W phase were calculated. The results show that increasing the initial Zn/Gd ratio in as-cast alloys increases the ratio of I and W phases, increasing the content of Zn and Gd under a certain Zn/Gd ratio increases the amount of I and W phases simultaneously. I phase and W phase form in the residual melt of primary α-Mg crystallization, the changes of the distribution of Zn and Gd in the alloy will affect the composition of the residual melt, thus affecting the forming ability of I phase and W phase. After homogenization, I phase disappears, W phase increases and total amount of ternary phase decreases. The Gd element in the newly formed W phase comes from the decomposed I phase and the supersaturate solid solution, while the Zn decomposed from I phase and more than that required for the newly formed W phase diffused to the solid solution.

Joint Effect of Samarium and Holmium on the Strength Properties of Mg–Y–Gd–Zr Alloys

The joint effect of samarium and holmium on the properties of an IMV7-1 Mg–Y–Gd–Zr alloy in two different states, namely, homogenized and homogenized and subsequently aged at 200°C to the peak strength, has been studied at testing temperatures of 20 and 250°C. Samarium and holmium do not change the behavior of the Mg–Y–Gd–Zr alloys during aging; at the same time, the presence of ~4% Sm in the alloys accelerates the decomposition of the magnesium solid solution and increases their strength properties, and the presence of 2 to 5% Ho in the IMB7-1 alloys containing 4% Sm leads to a decrease in their strength properties.

Deformation Mechanisms and Evolution of Second Phase Particles of Mg–Y–Nd–Gd–Zr Alloy During Plane Strain Compression

Deformation Mechanisms and Evolution of Second Phase Particles of Mg–Y–Nd–Gd–Zr Alloy During Plane Strain Compression

Effect of extrusion on the microstructure and corrosion behaviors of biodegradable Mg–Zn–Y–Gd–Zr alloy

Magnesium-based alloys presented great potential for biodegradable implant materials. However, the poor mechanical properties and high corrosion rate blocked its extensive application. In this study, a new biodegradable Mg–Zn–Y–Gd–Zr alloy was fabricated and extruded. The microstructure, corrosion morphologies and corrosion products film of the as-cast, homogenized and as-extruded alloys were characterized by optical micrographs, scanning electron microscopy, X-ray diffraction and laser scanning confocal microscopy. Moreover, the corrosion mechanisms of the as-cast and as-extruded alloys were proposed, and the influencing factors of corrosion properties were discussed. The electrochemical test, immersion tests and corrosion morphologies demonstrated that the as-extruded alloy exhibited favorable corrosion properties. The as-cast and homogenized alloys displayed localized corrosion mode, and the as-extruded alloy displayed uniform corrosion mode. The Volta potential of the Mg3(Y,Gd)2Zn3 phase relative to Mg matrix was measured by using Kelvin probe force microscopy.

Interaction of the Components in the {Ce, Gd}-{Ti, Zr}-Sb Systems

The phase equilibria in the ternary systems {Ce, Gd}–{Ti, Zr}–Sb were investigated by means of X-ray powder diffraction and energy-dispersive X-ray spectroscopy. The isothermal sections of the phase diagrams at 600°C were constructed. The formation of three ternary compounds (Ce2Ti7Sb12, Ce3TiSb5, and Gd2Ti11Sb14) was confirmed in the {Ce, Gd}–Ti–Sb systems and no more ternaries were found. The investigation of the {Ce, Gd}–Zr–Sb systems revealed several new ternary compounds and confirmed the known ones. The crystal structure of the new compound Ce0.08(3)Zr1.92(3)Sb was determined from X-ray powder diffraction data. The other new compounds in the Ce–Zr–Sb system were found to have compositions close to ~CeZrSb4and ~Ce2Zr3Sb5. In the Gd–Zr–Sb system the existence of a large homogeneity range was established for the GdZrSb compound along the isoconcentrate 33.3 at.% Sb: Gd1-xZr1+xSb (x= 00.905(18) at 600°C), and a new compound, ~Gd3Zr3Sb14, was discovered. The crystal structures at the boundary compositions of the Gd1-xZr1+xSb phase were refined from X-ray powder diffraction data.

Effect of Cerium and Erbium on the Aging Kinetics and the Properties of an IMV7-1 Alloy of the Mg–Y–Gd–Zr System

The effect of additional alloying of an IMV-7 alloy of the Mg–Y–Gd–Zr system with other rare-earth metals, in particular, cerium and erbium, is studied. The hardness and the electrical resistivity of the alloys, which characterize the kinetics of supersaturated solid solution decomposition upon aging at 200°C, are presented. The hardness and the mechanical properties of the alloys at high temperatures (250, 300°C) are measured. The microstructure of the alloys after heat treatment is examined. Cerium in the content range under study is found to exert no effect on the properties of alloys, such as IMV7-1, whereas erbium is undesirable and can decrease their hardening upon aging.

Effect of heat treatment on microstructures and mechanical properties of Mg–Zn–Gd–Zr alloys with different compositions

Effect of heat treatment on microstructures and mechanical properties of Mg–Zn–Gd–Zr alloys with different compositions

Effect of Samarium on the Properties of Mg–Y–Gd–Zr Alloys

The microstructure, the aging kinetics, and the strength properties of Mg–Y–Gd–Zr cast alloys, in particular, a samarium-alloyed IMV7-1 alloy, at room and high (250, 300°C) temperatures after homogenization without and with subsequent aging are studied. Alloying with samarium accelerates the decomposition of the supersaturated magnesium solid solution and enhances the properties of the Mg–Y–Gd–Zr alloys.

On the role of Ag in enhanced age hardening kinetics of Mg–Gd–Ag–Zr alloys

The addition of Ag to the age hardenable Mg–Gd–Zr alloy system dramatically enhances early stage age hardening kinetics. Using atom probe tomography (APT), Ag-rich clusters were detected in a Ag-containing Mg–Gd–Zr alloy immediately after solution treatment and water quenching. During subsequent isothermal ageing at 200 °C, a high density of basal precipitates was observed during the early stages of ageing. These basal precipitates were enriched with Ag and Gd, as confirmed by APT. It is posited that Ag-rich clusters in the context of quenched-in vacancies can attract Gd atoms, increasing diffusion kinetics to facilitate the formation of the Ag + Gd-rich basal precipitates. The rapid formation of Ag + Gd-rich precipitates was responsible for accelerated ageing.