Effect Of Ge Addition Research Articles

Effect of Ge addition on the clustering of naturally-aged Al–Mg–Si–Cu alloy

Ge addition effect on the delaying natural aging of Al–Mg–Si–Cu alloy was investigated. Natural aging kinetic and cluster size was suppressed by the Ge addition. Using atom probe tomography, it was found that Ge refines cluster evolution by disturbing Mg-enrichment of Si–Si cluster as well as enhancing vacancy trapping. Segregation of Ge at the interface of cluster was also regarded as potential barrier to growth of the clusters.

Effects of Ge addition on the structure, mechanical and magnetic properties of (CoCrFeNi)100-xGex high-entropy alloys

Alloying non-metallic elements can not only change the structure of alloys, but also tailor the mechanical and physical properties. The microstructure, mechanical and magnetic properties of (CoCrFeNi)100-xGex (molar ratio, x = 0 ∼ 33) high-entropy alloys (HEAs) have been systematically studied in this paper. The experimental results show that the (CoCrFeNi)100-xGex HEAs transform from a face-centered cubic (FCC) to a body-centered cubic (BCC) solid solution when 10 ≤ x ≤ 25, and a hexagonal intermetallic compound (IM) formed at x = 33. Tensile measurement revealed that the strength and plasticity of the alloy were enhanced simultaneously with Ge addition in the single FCC region (x ≤ 10), a decrease in ductility but sharp increase of strength was found in the alloys when the BCC phase starts to appear. Theoretical calculations and magnetic hysteresis loop measurements show that the alloys transform gradually from a paramagnetic to a ferromagnetic state at room temperature.

Grain refinement of primary Cu6Sn5 in the Sn-3wt%Ag-5wt%Cu alloy by Ge

Fine grain structure is generally favoured in the alloy system. Here, we demonstrate that the fine intermetallic compounds (IMCs) in Sn-3wt%Ag-5wt%Cu (SAC35) alloy by coupling with different amount of Ge (0–0.15wt%). The effect of Ge addition on the microstructure, elemental distribution, thermal properties, solidification, and corresponding grain refinement mechanisms were studied. The results showed that Cu6Sn5 was explicitly refined in Ge added SAC35 alloys, with a maximum 59% reduction in the size of Cu6Sn5 found in the as-cast bulk SAC35-0.1wt%Ge alloy. Also, the presence of Ge reduced the thickness and grain size at the interfacial IMC layer by 21% and 22%, respectively. Synchrotron micro-XRF results revealed that the Ge preferentially exist in matrix phase. The cooling curve analyses revealed that the solidification time of Ge-coupled is shorter than that of the SAC35 alloy. The undercooling values was found to have decreased with increased Ge addition. The growth restriction factor, Q, was calculated with the aid of Thermo-Calc software, and it was found to have increased in tandem with increasing Ge amounts. The findings suggest the suitability of Ge as a grain refiner for SAC35.

The effect of Ge addition on the optical and physical properties of thermally evaporated amorphous Pb15Se85-xGex (x = 0, 3, 6, 9, 12) thin films and bulk glasses

The effects of the addition of Ge on the optical and physical properties of a-Pb15Se85-xGex (x = 0, 3, 6, 9, 12 at. %) vacuum evaporated thin films are discussed in the given paper. An X-ray diffraction analysis of the films reveals no sharp peaks, indicating their amorphous nature. Transmission spectra of normal incidence were measured in the spectral window of 500 nm–2400 nm. An absorption edge shift has been observed with the addition of Ge at the expense of Se. Swanepoel analysis was applied to compute the refractive index values. Absorption losses were also calculated and discussed. The increase in Ge addition changes the refractive index and absorption coefficient. The bandgap transition is indirect and experimentally calculated using the Tauc-extrapolation method. Penetration depth and optical density were also calculated. WDD model was applied and static refractive index and WDD parameters were evaluated. Theoretical parameters viz. Cohesive energy, average heat of atomization, compactness, polaron radius were also calculated. Efforts were made to correlate obtained optical and physical parameters of the system.

Effect of Ge Addition on Magnetic Properties and Crystallization Mechanism of FeSiBPNbCu Nanocrystalline Alloy with High Fe Content

In this work, new Ge-containing Fe-based nanocrystalline alloys with the composition of Fe80.2Si3B12-xP2Nb2Cu0.8Gex (x = 0, 1, 2 at.%) were developed, and the effects of Ge content on the magnetic and crystallization processes of the alloys were investigated. The addition of Ge extends the annealing window of the present Fe-based alloys, which reaches 173.6 K for the alloy of x = 2. The nanocrystalline alloy of x = 2, composed of dense and uniformly distributed α-Fe grains with an average grain size of 15.7 nm precipitated in the amorphous matrix, was obtained by conventional annealing treatment at a temperature of 843 K for 10 min, and this nanocrystalline alloy exhibited excellent magnetic properties with the Hc of 3 A/m and Bs of 1.65 T, which has great potential for industrial application. Non-isothermal crystallization kinetics studies show that the nucleation activation energy of the alloys gradually decreases with the increase in Ge content. The primary crystallization process is dominated by the direct growth of pre-existing nuclei in the as-spun alloy ribbons, and these pre-existing nuclei provide numerous heterogeneous nucleation sites to form dense and uniform α-Fe nanocrystals with a fine grain size, which leads to the excellent magnetic properties of the present Ge-containing Fe-based nanocrystalline alloys.

Effect of Ge addition on the microstructure, mechanical properties, and corrosion behavior of CoCrFeNi high-entropy alloys

Based on the results of many studies devoted to exploring the effect of adding different elements to CoCrFeNi alloys in the field of high-entropy alloys, in this study, Ge is included in CoCrFeNi alloys to form CoCrFeNiGex alloys (molar ratio, x = 0, 0.1, 0.2, and 0.3). Ge is used to improve mechanical properties and corrosion resistance of traditional alloys, but its application in high-entropy alloys has been less discussed. CoCrFeNiGex alloys (x ≤ 0.3) exhibit a single face-centered cubic phase. Tensile testing of these alloys revealed that the CoCrFeNiGe0.3 alloy exhibited slightly better mechanical properties—a yield strength of 223 MPa, ultimate tensile strength of 617 MPa, and elongation of 63.2%—due to solid-solution hardening. A potentiodynamic polarization test in deaerated 3.5% NaCl solution showed that Ge addition can effectively inhibit pitting corrosion and can improve the corrosion resistance of CoCrFeNi alloys by reducing the corrosion and passive current density.

Effect of Ge-addition on physical and optical properties of chalcogenide Pb10Se90-xGex bulk glasses and thin films

Several substantial physical and optical properties of non-crystalline Pb10Se90-xGex bulk glasses and thin-films (0.0 ≤ x ≤ 10 at.%) have been studied. Bulk and film samples were synthesized via melt-quench and thermal-evaporation processes, respectively. The films were fabricated on pre-cleaned glass substrates under vacuum ≈5 × 10−4 Pa. The non-crystallinity of studied samples has investigated by X-ray diffractograms. A good-matching between selected compositional elements and those measured experimentally was confirmed by energy-dispersive X-ray analysis. The absorption nature of samples was studied in detail, where absorbance, absorption coefficient, skin depth and skin effect were discussed. The indirect transition bandgap energy was studied and its value decreases as Ge-content increases. Cohesive energy, average coordinate number, average atomization heat, lone-pair electrons, mean-bond energy, and others were discussed. Based on density values, many parameters were estimated and studied, like compactness, packing density, atomic densities, polaron radius, field strength. All studied characterizations are strongly dependent upon Ge-percentages.

The Effect of Ge Addition on the Oxidation of Nb-24Ti-18Si Silicide Based Alloys.

In this paper, we report research about the isothermal oxidation in air at 800 and 1200 °C for 100 h of the as-cast alloys (at.%) Nb-18Si-5Ge (ZF1), Nb-18Si-10Ge (ZF2), Nb-24Ti-18Si-5Ge (ZF3), Nb-24Ti-18Si-5Cr (ZF4), Nb-24Ti-18Si-5Al (ZF5), Nb-24Ti-18Si-5Al-5Cr-5Ge (ZF6), and Nb-24Ti-18Si-5Al-5Cr-5Ge-5Hf (ZF9), the microstructures of which were reported in previous publications. Only the alloys ZF1, ZF2, and ZF3 suffered from pest oxidation at 800 °C. The Ge addition substantially improved the oxidation resistance of the other alloys both at 800 °C and 1200 °C, which followed parabolic kinetics at 800 °C and in the early stages at 1200 °C and linear kinetics at longer times, where there was spallation of the scales. The Nb2O5 and TiNb2O7 oxides were formed in the scales of the alloys ZF4, ZF5, ZF6, and ZF9 at 800 °C and 1200 °C, the GeO2 was observed in all scales and the SiO2 in the scales of the alloys ZF4 and ZF5, the CrNbO4 in the scales of the alloys ZF4, ZF6, and ZF9 and the AlNbO4 in the scales of the alloys ZF5, ZF6, and ZF9. Diffusion zones were formed below the scale/substrate interface only in the alloys ZF4 and ZF5 where the Nbss and Nb5Si3 were contaminated by oxygen. However, these phases were not contaminated by oxygen in the bulk of the alloys ZF4, ZF5, ZF6, and ZF9. The alloys ZF9 and ZF6 exhibited the best oxidation behaviour at 800 °C and 1200 °C, respectively. The alloys were compared with Nb-silicide based alloys of similar compositions without Ge and Hf additions and the alloy ZF9 with refractory metal High Entropy Alloys. Compared with the former alloys, the addition of Ge reduced the vol % of the Nbss. Compared with the latter alloys, the superior oxidation behaviour of the alloy ZF9 was attributed to its higher and lower values respectively of the parameters δ and VEC.

Effects of Ge addition on thermoelectric properties in a nanocomposite of MnSiγ and SiGe thin films

..Abstract In this work, we fabricated nanocomposite thin films of MnSiγ and SiGe, both of which are promising thermoelectric materials, and studied the dependence of their crystal structures and thermoelectric properties on the Ge content. The addition of Si1-xGex caused a reduction in the grain size of the MnSiγ matrix to the scale of the phonon mean free path of MnSiγ, which is essential for phonon scattering to reduce the lattice thermal conductivity. In addition, increasing the Ge ratio in the additive SiGe of the nanocomposite caused both a reduction at x = 0.2 ratio in the thermal conductivity and a monotonical reduction of the electrical resistivity with negligible change in the thermopower. The former of these two phenomena may be attributed to both a reduction in the thermal conductivity of SiGe as a result of heavier element (Ge) substitutions than Si and an increase in the thermal boundary resistance between MnSiγ and SiGe. In the case of the latter, introduction of carriers caused by the decrease in γ, which is the atomic ratio between Si and Mn, would be responsible. As a result, the estimated thermoelectric dimensionless figure-of-merit ZT increased to reach a maximum of 0.43 at 459 °C, which is larger than that of the single phase MnSiγ film, without any doping into the MnSiγ matrix with heavy elements.

Improved microstructure and thermoelectric properties of higher manganese silicide processed by reactive spark plasma sintering

In this paper, the crystal structure, microstructure, thermoelectric properties and figure of merit (zT) of highly pure higher manganese silicide (HMS) alloys are reported and discussed without the bias generally introduced by impurities in published results. The alloys were produced by both solid-state reaction diffusion assisted by spark plasma sintering and conventional arc melting in order to evaluate the effect of the process on the microstructure and on the resulting properties of HMS. The effect of Ge addition is also explored. Properties diagram for thermoelectric materials is displayed to assess the performance of un-doped and Ge-doped HMS alloys in comparison with the state of the art. Electrical conductivity and zT at 500 °C of the HMS alloys studied here exceed published properties achieved with similar alloys, providing new process options for reliable, affordable and efficient thermoelectric applications.

Effect of Ge addition on wettability, copper dissolution, microstructural and mechanical behavior of SnCu–Ge solder alloy

This paper explores the effects of Germanium (Ge) addition on the wetting behavior, copper dissolution, IMC formation, microstructure and mechanical behavior of SnCu alloy. Static copper dissolution was conducted as a function of contact time and in the temperature range of 260–300 °C. The results show that the Ge doped alloy has the lowest copper dissolution rate compared to SnCu, SAC305, and very much comparable with SnPb solder thus making it suitable alloy for the wave soldering process. Two solderability standards measurement (JIS vs. IPC) have been executed on different surface finishes such as OSP, ENIG, ImAg commonly used in industrial soldering process. The results showed that addition of Ge significantly improves the wetting/spread performance for all the surface finishes (ENIG, OSP and ImAg). Contact angles range from 17°–30°, the lowest contact angles being observed on ENIG surface. Microstructural analysis showed Ge addition refine the grain structure of SnCu–0.01Ge alloy. A thin IMC layer was observed, and IMC growth was not significant after multiple reflows as compared to Sn–Cu alloy. Similarly, Ge addition increases the hardness value due to uniform microstructure of SnCu–Ge alloy. The tensile testing results also showed an increase in tensile strength and tolerable ductility.

Effect of Ge addition on structure and soft magnetic properties of Si-rich Fe-based nanocrystalline alloys

Soft magnetic Fe72.7Al0.8Si17.5B5Cu1Nb3-xGex (x = 0, 0.2, 0.4, 0.6, 0.8 and 1.0) amorphous alloys were produced by the single roller melt spinning method. The effects of Ge substitution for Nb on the microstructure and magnetic properties were investigated. Magnetic properties of all the alloys annealed at different temperatures were measured by the temperature dependence of initial permeability (μi-T curves) from the ambient temperature up to 650 °C. Structure and crystalline process have been analyzed by XRD patterns and DSC curves, respectively. Partial substitution of Nb by Ge enhanced the Curie temperatures of amorphous phase and crystalline phase, and therefore improved the soft magnetic properties at high temperature. The Fe72.7Al0.8Si17.5B5Cu1Nb2.6Ge0.4 alloy annealed at 570 °C for 0.5 h shows the optimum high-temperature μi, together with higher room-temperature μi. The origin of the improved magnetic softness both at room- and high-temperature was analyzed.

Oxide microstructural evolution of Zr–0.7Sn–0.35Nb–0.3Fe alloys containing Ge corroded in lithiated water

The results of corrosion tests conducted in lithiated water with 0.01M LiOH at 360°C/18.6MPa revealed that the corrosion resistance of the Zr–0.7Sn–0.35Nb–0.3Fe alloy in wt% was considerably improved by Ge addition of 0.05–0.2wt%. To further understand the mechanism on the effect of Ge addition on the corrosion resistance of the Zr–0.7Sn–0.35Nb–0.3Fe alloy in wt%, the microstructures of alloys and oxides were investigated by transmission electron microscopy and scanning electron microscopy. For the Zr–0.7Sn–0.35Nb–0.3Fe–0.2Ge alloy, the outer layer of oxide mainly consisted of equiaxed grains, while the middle layer of oxide mainly consisted of many columnar grains in a direction perpendicular to the oxide/metal interface. The suitable amount of Ge can retard the evolution from the columnar grains to the equiaxed grains and delay the developing process of the defects to form the micro-cracks in oxide. The amorphous phase produced around the [Zr(Fe,Cr,Nb,Ge)2]O SPPs could relax the compressive stress, which could improve the corrosion resistance of zirconium alloy. The corrosion resistance could be degraded by the formation of cracks from the coarse [Zr3Ge]O SPPs towards the outer surface of oxide layers.

Glass transition and crystallization kinetics analysis of Sb–Se–Ge chalcogenide glasses

Differential thermal analysis (DTA) has been employed to investigate the effect of Ge addition on the glass transition behavior and crystallization kinetics of Sb10Se90−xGex (x = 0, 19, 21, 23, 25, 27) alloys. The three characteristic temperatures viz. glass transition (T g), crystallization (T c), and melting (T m) have been determined and found to vary with the heating rates and Ge content. Thermal stability and glass forming tendency have been evaluated in terms of ΔT (= T c − T g) and reduced glass transition temperature. The activation energies for glass transition and crystallization have been used to analyze the nucleation and growth process. The activation energy analysis also determines the suitability of alloys to be used in switching applications. Results have been interpreted in terms of bond energies and structural transformations in the investigated alloys.

The effect of Ge addition on Al–3.5Cu–0.4Mg (wt.%) alloy

A trace (0.2 wt.%) addition of Ge significantly increased both the strength and elongation of Al–3.5Cu–0.4 Mg alloy. An aged Al–3.5Cu–0.4 Mg–0.2Ge (wt.%) alloy revealed good tensile properties after being exposed at 150 °C. Transmission electron microscopy observations showed that these properties are closely correlated to the high-density microstructure of nanoscale precipitates and the good coarsening resistance of those precipitates; Ge stimulated the formation of nanoscale precipitates and suppressed the formation of S′ precipitates in aged Al–3.5Cu–0.4 Mg–0.2Ge (wt.%) alloy.

Phase transformation and mechanical properties of (Ni56.5Fe17Ga26.5)100−xGex ferromagnetic shape memory alloys

Abstract The effect of Ge addition on the microstructure, transformation temperatures and mechanical properties of (Ni56.5Fe17Ga26.5)100−xGex ferromagnetic shape memory alloys was investigated. With the increase of Ge content in these alloys the martensitic transformation temperatures decrease almost linearly from higher than 100 °C down to −70 °C or even lower that is attributed to the change of the electron concentrations of the Ni–Fe–Ga(Ge) alloys. The addition of Ge also significantly enhances the compression strength and the ductility of the alloys. The determined relationships between transformation temperatures and the mechanical properties and the Ge content will be useful for designing a suitable Ni–Fe–Ga(Ge) alloy device with a required martensitic transformation temperature and optimized mechanical property.

Effect of Ge addition on mechanical properties and fracture behavior of Cu–Zr–Al bulk metallic glass

Effect of the addition of a small amount of Ge on mechanical properties and fracture behavior of Cu 50Zr 43Al 7 (at.%) bulk metallic glass were studied. The Cu 50Zr 43Al 7 alloy has a surprising glass-forming ability (GFA), and the glassy rods up to 4 mm in diameter can be formed. Partial addition of Ge causes the crystalline phases precipitate in the glassy matrix of (Cu 50Zr 43Al 7) 100− x Ge x ( x = 0, 1, 2) rods with a diameter of 4 mm. In uniaxial compression, Cu 50Zr 43Al 7 bulk metallic glass exhibit high strength of 1692 MPa and very limited plasticity of 0.05%. When Ge increases from 0 to 2 at.%, the strength decreases, but plastic strain increases about 2.5%. Fracture surface and shear bands of samples were investigated by scanning electron microscopy (SEM).

Transformation temperatures in polycrystalline Ni 56.5− xFe 17 Ga 26.5Ge x ferromagnetic shape memory alloys

The effect of Ge addition on the microstructure and martensitic transformation of polycrystalline Ni 56.5Fe 17Ga 26.5 shape memory alloy was investigated using optical metallography technique, X-ray diffraction and differential scanning calorimeter. The results showed that the martensitic transformation temperatures decrease monotonously with the increase of fraction of Ge substitution for Ni. The decrease of the transformation temperatures should be related to the change of the electron concentration after the addition of Ge in NiFeGa alloys.

Effect of Ge addition on the martensitic transformation temperatures of Ni–Fe–Ga alloys

A systematical study of substitution of Ge for Ni, Fe, and Ga in the non-stoichiometric NiFeGa alloys was performed in this work. The effect of Ge addition on the structure and martensitic transformation in NiFeGa alloys was investigated by an optical microscope, X-ray diffraction, and differential scanning calorimeters. The results show that the transformation temperatures decrease almost linearly with increasing Ge content in all the three types from higher than 100 down to −90 °C and even lower. The decreases in rate of the martensitic transformation temperatures are different for the three cases. It is large for Ni substituted by Ge, slow for Ga and intermediate for Fe. The determined relationship will be significant for designing a suitable NiFeGa alloy with a required martensitic transformation temperature for application at specific temperature.

Effect of Ge Addition on the Optical Band Gap and Refractive Index of Thermally Evaporated Thin Films

The present paper reports the effect of Ge addition on the optical band gap and refractive index of thin films. Thin films of and were prepared by thermal evaporation technique at base pressure Pa. Optical band gap and refractive index were calculated by analyzing the transmission spectrum in the spectral range 400–1500 nm. The optical band gap decreases while the refractive index increases with the addition of Ge to . The decrease of optical band gap has been explained on the basis of density of states; and the increase in refractive index has been explained on the basis increase in disorder in the system.