Increasing Bi Content Research Articles

Kinetic and structural insights into the grain boundary phase transitions in Ni-Bi alloys

Kinetic and structural changes associated with grain boundary phase transition induced by Bi alloying in dilute Ni–Bi alloys (0–0.3 at.% of Bi) are investigated in a concerted manner. Grain boundary diffusion of Ni in the Ni-Bi alloys is measured in Harrison's B- and C-type kinetic regimes applying the radiotracer technique and utilizing the 63Ni radioisotope. The measurements are performed across the single phase towards two-phase regions of the bulk phase diagram. In case of the single phase region it is the Ni(Bi) solid solution. In case of two phase areas these are Ni(Bi) solid solution + liquid Bi above 927 K or Ni(Bi) solid solution + NiBi below 927 K. Three distinct regions of the dependence of the Ni grain boundary diffusion rates on the Bi concentration are distinguished. A slight increment in Ni grain boundary diffusion is observed at lower Bi contents which is driven by Bi grain boundary segregation. Beyond a critical Bi concentration and still within the single-phase solid solution region, the Ni diffusivity starts to enhance dramatically with increasing Bi content. This is correlated with the appearance of multi-layer Bi segregation along the grain boundaries. It is substantiated by high-angle annular dark-field scanning transmission electron microscopy combined with energy dispersive X-ray spectroscopy measurements. At higher Bi concentrations, which corresponds to the appearance of a liquid layer of Bi at the grain boundaries, the Ni diffusivity attains the highest values. A serial of structural transitions between the different grain boundary phases is for the first time demonstrated to be accompanied by remarkable changes of the grain boundary diffusion rates. The present results highlight a close correlation between the atomic transport and structure modifications due to grain boundary phase transitions in the Ni–Bi alloys. Utilizing the present experimental results, a Ni–Bi grain boundary diffusion map is proposed.

Effects of Bi Alloying on the Thermoelectric Properties of p‐Type Mg3Sb2‐xBix Solid Solutions

AbstractBismuth is the most common alloying element for high‐performance Mg3Sb2‐based thermoelectric compounds. However, the electrical and thermal transport data is lacking for undoped Mg3(Sb, Bi)2 solid solutions. In this study, theoretical calculation results show that Bi alloying can reduce the band gap of Mg3Sb2, favoring the regulation of carrier concentration. Both Mg3Sb2 and Mg3SbBi compounds present a single band structure on the valence band maximum at Γ of the Brillouin zone. Incorporating the Bi element can slightly increase the density of states (DOS) on the valence band maximum, which is beneficial for the Seebeck coefficient. Mg3Sb2‐xBix (0≤x≤0.8) compounds were experimentally prepared via ball milling (BM) combined with the spark plasma sintering (SPS) technique. The carrier concentration, electrical conductivity, and power factor of the samples tend to increase with the increasing Bi content. Bismuth alloying significantly reduces the total thermal conductivity in the low‐temperature range, with the lowest value of 0.65 Wm−1K−1 obtained at ∼400 K for the x=0.2 sample. The peak ZT value of 0.077 at 800 K and the average ZT of 0.051 in the temperature range of 450–800 K are obtained for the x=0.2 sample, which is 93% and 219% higher than those of the unalloyed sample, respectively. This work reveals the Bi‐alloying induced transport mechanism and provides fundamental thermoelectric data regarding the undoped Mg3Sb2‐xBix (0≤x≤0.8) solid solutions.

Enhancing the thermoelectric power factor of nanostructured SnO2 via Bi substitution

Tin dioxide (SnO2) has recently proved to be a promising material for thermoelectric applications. We have investigated the influence of highly valence Bi doping as an electron donor in oxygenated SnO2 materials on their thermoelectric properties. We have synthesized the pure and Bi doped SnO2 nanoparticles (x = 0%, 5%, 10%, and 15%) through a simple hydrothermal approach. The Seebeck coefficient and Hall measurements have been used to determine thermoelectric behaviour. The measured value of the Seebeck coefficient increases from - 56 to - 83 μV/°C as the Bi content increases. This improvement in the Seebeck coefficient has been attributed to the charge carrier localization (energy filtering effect) caused by the inclusion of the bismuth atoms and the presence of secondary phases based on BiO2. However, the electrical conductivity measurements show an inverse relation with the Bi doping, increasing the impurities. The Sn1-xBixO2 sample with x = 15 has achieved the maximum Seebeck value, resulting in the upward trend in power factor of up to 1.97 × 10−4 Wm−1C−2. Further, we have used X-ray diffraction and scanning electron microscopy to determine the effect of Bi on the SnO2 crystal structure and surface morphology. Which also demonstrates the presence of composites with mixed phases.

Indentation creep behaviour of the magnesium AZ61–0.7Si–xBi cast alloys

Creep behaviour of the AZ61–0.7Si–xBi cast magnesium alloys were studied by Vickers indentation testing under constant load of 5 N in the temperature range of 423–523 K. The results indicate that increasing Bi content improved the creep resistance at all test temperatures. This was caused by the higher volume fraction of the thermally stable Mg3Bi2 intermetallic particles, as the principal strengthening cause, which compensated the possible effects of the lower amount of the Mg2Si particles. According to the obtained stress exponents of about 6.7 and activation energies in the range of 84.6–88.1 kJ mol−1, dislocation pipe diffusion was suggested as the dominant creep mechanism.

Zintl Phase Compounds Mg3Sb2−xBix (x = 0, 1, and 2) Monolayers: Electronic, Phonon and Thermoelectric Properties From ab Initio Calculations

The Mg3Sb2−xBix family has emerged as the potential candidates for thermoelectric applications due to their ultra-low lattice thermal conductivity (κL) at room temperature (RT) and structural complexity. Here, using ab initio calculations of the electron-phonon averaged (EPA) approximation coupled with Boltzmann transport equation (BTE), we have studied electronic, phonon and thermoelectric properties of Mg3Sb2−xBix (x = 0, 1, and 2) monolayers. In violation of common mass-trend expectations, increasing Bi element content with heavier Zintl phase compounds yields an abnormal change in κL in two-dimensional Mg3Sb2−xBix crystals at RT (∼0.51, 1.86, and 0.25 W/mK for Mg3Sb2, Mg3SbBi, and Mg3Bi2). The κL trend was detailedly analyzed via the phonon heat capacity, group velocity and lifetime parameters. Based on quantitative electronic band structures, the electronic bonding through the crystal orbital Hamilton population (COHP) and electron local function analysis we reveal the underlying mechanism for the semiconductor-semimetallic transition of Mg3Sb2-−xBix compounds, and these electronic transport properties (Seebeck coefficient, electrical conductivity, and electronic thermal conductivity) were calculated. We demonstrate that the highest dimensionless figure of merit ZT of Mg3Sb2−xBix compounds with increasing Bi content can reach ∼1.6, 0.2, and 0.6 at 700 K, respectively. Our results can indicate that replacing heavier anion element in Zintl phase Mg3Sb2−xBix materials go beyond common expectations (a heavier atom always lead to a lower κL from Slack’s theory), which provide a novel insight for regulating thermoelectric performance without restricting conventional heavy atomic mass approach.

Comprehensive study on structure, mechanical and nuclear shielding properties of lead free Sn–Zn–Bi alloys as a powerful radiation and neutron shielding material

Various compositions of 60Sn- (40-x) Zn – xBi (where x = 0, 10, 20, 30, 40 wt%) rapidly solidified alloys have been prepared by melt-spinning technique. The structural and mechanical properties have been investigated by X-ray diffraction (XRD) and tensile test machine techniques respectively. Additionally, the nuclear shielding performance of the prepared alloys was examined. XCOM software was used to compute the μm values across a large energy range of 0.015 MeV–15 MeV. To clearly comprehend the radiation and neutron shielding capabilities of the prepared alloys, various parameters such as mass attenuation coefficient (μm), half value layer (HVL), total atomic (σa) and total electronic cross-sections (σe), effective atomic number (Zeff), exposure buildup factor (EBF), energy absorption buildup factors (EABF), specific absorbed fraction of energy (SAFE) and macroscopic effective removal cross section (ΣR) were computed and compared to other commonly shielding materials. The results revealed that increasing Bi content leading to decreasing the crystal size which enhances the mechanical and radiation shielding properties. The Sn-40% Bi (S5) alloy shows a maximum increase of the Young's modulus value of 90.5 GPa, the tensile strength of 299.9 MPa, yield strength of 267.9 MPa, μm, Zeff, and ΣR of 0.1016 cm−1. The results also show that, HVL, MFP, EBF, EABF and SAFE values are all lowest in the S5 alloy. As a result, the S5 alloy may be regarded a preferable material for radiation shielding applications. The findings of this research might be very beneficial in the future for nuclear waste storage, medical and industrial uses.

The Effect of Bismuth on Technological and Material Characteristics of Low-Alloyed Automotive Steels with a Good Machinability

The aim of this work is to compare the technological and material properties of CMnCr steels without bismuth, with 0.08 wt. % Bi and 0.12 wt. % Bi. Experimental heats showed that the most advantageous alloying of Bi into the heat was in the ladle, with an efficiency of about 20%. The optimal temperature range for forming steel was found to be 1160–1050 °C. With increasing Bi content, the formability of steels and plastic properties decreased, while the yield stress and tensile strength increased. Manganese sulfides, aluminum oxides, or oxysulfides, which were segregated both individually and in clusters, were found in the matrix of all tested steels. In steels with Bi, the Bi particles segregate the separately in the form of globules, either as envelopes of elongated MnS or Al2O3 particles segregated in rows. Sulfur dot-shaped segregations in the steel with 0.12 wt. % of Bi and the steel without Bi were essentially uniform over the whole area. For the steel with 0.08 wt. % of Bi, both dot-like and ray-ordered sulfur segregations were observed. The microstructure of all tested steels was ferritic–pearlitic with islands of bainite. Towards the center of the forged bars, variable shape and size of bainite blocks were observed. Machinability tests evaluated by the extend of tool wear showed that the most advantageous was CMnCr steel alloyed with 0.08 wt. % Bi.

Effect of Bi doping on the structure and wave absorption properties of barium ferrite

Bi x Ba 1- x Fe 12 O 19 (Bi–BFO, x = 0, 0.1, 0.2, 0.3, 0.4) absorbing materials were successfully prepared employing the sol-gel method. In this study, the effects of Bi introduction on the phase structure, microstructure, magnetic properties, and wave absorption properties of the materials were investigated in detail. The introduction of Bi enhances the dielectric properties and electrical conductivity of the material, which improves charge and dipole polarization. Elemental doping changes the microstructure of the sample, which leads to interface and defect polarization and improves the wave absorption performance of the material. At the same time, Bi doping allows for the calcination temperature to be lowered and increases the density of the material, which renders the material amenable to low-temperature preparation. The absorbing material has a variety of loss forms, with the maximum reflection loss being −43.6 dB when the thickness is 2.4 mm, and the reflection peak shifts to lower frequencies with increasing Bi content. The effective absorption bandwidth (RL < −10 dB) is 6.3 GHz in the range of 9–15.3 GHz. Compared with multi-element doping and multi-component composites, the preparation method of the absorbing material is simple and facile. Compared with the existing ferrite materials, this material has broader applicability in various fields as it can absorb a wider bandwidth.

Phase transformation and crystallization study of Se100-xBix glassy alloys

Bulk Se100-xBix(x = 0, 5 and 10) glassy compositions were synthesized by the quenching method. The ingot materials were studied by X-ray diffraction, which was used to investigate the structure of the prepared compositions. Differential thermal analysis (DTA) under non-isothermal conditions was used to determine the transition temperatures, activation energies and responses of stability using various models such as Kissinger, Matusita, and Goa-Wang at four different heating rates. For a better understanding of the growth mechanism, the Avrami exponent (n) and the dimensionality of growth (m) have been studied. For the studied system, the obtained Avrami exponent values suggest surface nucleation with one-dimensional growth. The obtained results indicate that the thermal stability of the glassy samples decreases with increasing Bi content.

Significantly reduced conductivity in strontium titanate-based lead-free ceramics by excess bismuth

Lead-free dielectric ceramics 0.75SrTiO3-0.25BiFeO3 (ST-BF) with an extra amount of bismuth (Bi) are synthesized by the conventional solid-state reaction method. The crystal structures of ST-BF retain pseudo-cubic phase as Bi content increases. The grain size is found to significantly increase from 1.8 to 4.9 µm and then fall to 3.3 µm in the presence of excess Bi, exhibiting a distinct heterogeneous core–shell microstructure. Impedance spectroscopy data indicates that with increasing excess Bi content to 2 mol%, the shell resistivity increases significantly to ∼ 9 MΩ cm with the largest volume fraction of the shell/core area, and both the core and shell activation energies are increased, resulting in reduced dielectric loss of ∼ 0.08 at 1 kHz and high breakdown strength of ∼ 140 kV cm−1. This work provides a potential strategy for further improvement of ST-BF for capacitor applications.

Effects of Bi-doping on electronic structure and martensitic transformation in Ni2MnGa and Mn2NiGa MSMAs: A theoretical approach

The effects of Bi-doping on the electronic structure, martensitic transformation and magnetic properties of Heusler alloys Ni2MnGa1-xBix and Mn2NiGa1-xBix (x = 0, 0.25, 0.5, 0.75, 1) were investigated theoretically. The substitution of Bi for Ga has a negative effect on the martensitic transformation. The total energy difference ΔEM between the martensite and austenite decreases gradually with the doping of Bi. When x = 0.5, 0.75 and 1.0 in Ni2MnGa1-xBix and x = 1.0 in Mn2NiGa1-xBix, the martensite phase becomes higher in energy comparing with the austenite. Thus the doping of Bi can lower the martensitic transformation temperature TM and finally suppresses it. The possible reasons for this trend are related to the increasing valence electron concentration e/a and cell volume V with Bi-doping. The competition between them may be ascribed further by the electron density, which combines the effect of valence electron concentration and size effect. The electron densities of Ni2MnGa1-xBix and Mn2NiGa1-xBix decrease monotonously with increasing Bi content. This agrees well with the variation of ΔEM or TM. The doping of Bi does not change the magnetic structure of Ni2MnGa1-xBix and Mn2NiGa1-xBix. The former is ferromagnetic and the latter is ferrimagnetic in both martensite and austenite state. These results can help to introduce new component like Bi to Heusler alloys and discover new functional materials in them.

Interface interaction in CuBi catalysts with tunable product selectivity for electrochemical CO2 reduction reaction

Multi-componential catalyst design is an important strategy to boost electrochemical carbon dioxide reduction reaction (ECO2RR) performance. There still lacks an effective binary catalyst design to create an alternative opportunity of tuning the desiring product formation. Herein, we report a facile synthetic method of CuO/Bi(OH)3 anchored on carbon nanotubes (CNTs) by the two-step chemical hydrolysis in alkaline ethanol solution for ECO2RR. Bimetallic CuBi nanoparticles are demonstrated as electrocatalytical active centers. By varying the Cu:Bi atomic fraction, we report for the first time to tune the ECO2RR products selectivity from CO to formate. At −0.99 V vs. reversible hydrogen electrode (RHE), CuBi-#4 (YBi = 9.1%) and CuBi-#8 (YBi = 19.2%) exhibit the tunable CO and formate Faradaic efficiency (FE) as 60% and 96%, respectively, surpassing the monometallic counterpart in selectivity and activity. Small amount of Bi dramatically alters the catalytic behavior of Cu in CuBi-#4 by stabilizing the *COOH and weakening the binding strength of *CO to improve CO2-to-CO conversion. By further increasing Bi content, the CO2RR pathway is switched from *COOH to *OCHO, giving rise to a pronounced formate selectivity in CuBi-#8. This work highlights a new type of bimetallic catalyst to achieve the tunable products by fine composition design for the development of advanced catalyst and knowledge of mechanism.

Enhancing the thermoelectric performance of nanostructured ZnSb by heterovalent bismuth substitution

Eco-friendly Bi substituted ZnSb samples were prepared by a novel hydrogen decrepitation method, followed by consolidation using the cold pressing technique. The structural and morphological analysis of the samples have been carried out by XRD, FESEM and TEM. XRD analysis confirms the phase purity of the ZnSb sample. The presence of secondary phase of Bi was observed in the XRD patterns of Bi substituted Zn1-xBixSb (0.02 ≤ x ≤ 0.06) samples, probably due to low solid solubility limit of Bi in ZnSb alloy. FESEM and HRTEM images revealed the highly inter-connected grain structure and the grain sizes were in the range of 200 nm. The electrical resistivity and Seebeck coefficient values of Zn1-xBixSb samples were decreased compared to the pristine ZnSb sample. The power factor of Zn0.98Bi0.02Sb sample increased compared to pure sample. The thermal conductivity of Zn1-xBixSb alloys were increased with increasing Bi content (x). As a result, a high ZT of ~0.45 was achieved for Zn0.98Bi0.02Sb sample at 573 K compared to pure ZnSb (0.39). The experimental results demonstrated that bismuth substitution with optimum content is a promising approach to enhance the thermoelectric properties of ZnSb.

Synthesis and characterization of Bi-doped antimony sulphide thin films for solar absorption applications

Producing stable semiconducting thin films with low band gap energy by a viable technique is challenging for solar energy harvesting. Herein, Bi-doped Sb2S3 thin films have been deposited on glass substrates by chemical bath deposition (CBD) technique followed by annealing at 400 °C. X-ray diffraction (XRD) patterns confirmed the orthorhombic phase of Sb2S3 and successful incorporation of Bi+3 in the host lattice. Raman spectroscopy revealed the characteristic vibrational modes of Sb2S3. Surface of films became smoother and compact with increasing Bi contents. Samples showed wide absorption range in the visible region. Band gap energy (Eg) values were estimated using Tauc's relation and a blue shift in the absorption edge was observed with addition of Bi, thus Eg increased from 1.58 to 1.71 eV. Higher values of absorption coefficient and absorption edge in the visible region suggest that the prepared Sb2S3 thin films can be a right choice of an absorber layer.

Ice Bath Assisted BiMn2O5(Mullite) Phase Synthesis, Structural and Compositional Analysis under Different Bi Concentration

In this work, ice bath assisted co-precipitation synthesis of nanostructured Bismuth Manganite (BiMn2O5) with varied bismuth concentration and their consequences on the structural properties have rationally been investigated for first time in reports. The novelty of this study is to primarily elucidate the crystalline phase formations and related structural as well as compositional changes while fabricating BiMn2O5 with different amount of Bi content up to 20% to compensate the volatile Bi during annealing process. Powder X-ray diffraction and Rietveld Refinement techniques evidently confirmed the formation of single-phase mullite-type orthorhombic perovskite structure for stoichiometric ratio; while increasing Bi content, a secondary phase sillenite (Bi24Mn2O40) was formed which also gradually increased with increase in bismuth in the precursor solution. Rod and cubic shaped morphologies were commonly observed and size of the particles shows particle size ranging between 45 nm and 120 nm with increase of bismuth content. The mixed morphology is inevitably due to the presence of the secondary phases due to increasing Bi content that are evident from the XRD results. Raman and Optical properties evidently confirmed the structural variation and changes in the band gap respectively owing to the increase in secondary phase evolution with excess bismuth content. X-ray photoelectron spectroscopy (XPS) studies confirmed the increment in Bi content and the coexistence of Mullite and Sillenite phases in the samples.

Bismuth Doping in Nanostructured Tetrahedrite: Scalable Synthesis and Thermoelectric Performance.

In this study, we demonstrate the feasibility of Bi-doped tetrahedrite Cu12Sb4−xBixS13 (x = 0.02–0.20) synthesis in an industrial eccentric vibratory mill using Cu, Sb, Bi and S elemental precursors. High-energy milling was followed by spark plasma sintering. In all the samples, the prevailing content of tetrahedrite Cu12Sb4S13 (71–87%) and famatinite Cu3SbS4 (13–21%), together with small amounts of skinnerite Cu3SbS3, have been detected. The occurrence of the individual Cu-Sb-S phases and oxidation states of bismuth identified as Bi0 and Bi3+ are correlated. The most prominent effect of the simultaneous milling and doping on the thermoelectric properties is a decrease in the total thermal conductivity (κ) with increasing Bi content, in relation with the increasing amount of famatinite and skinnerite contents. The lowest value of κ was achieved for x = 0.2 (1.1 W m−1 K−1 at 675 K). However, this sample also manifests the lowest electrical conductivity σ, combined with relatively unchanged values for the Seebeck coefficient (S) compared with the un-doped sample. Overall, the lowered electrical performances outweigh the benefits from the decrease in thermal conductivity and the resulting figure-of-merit values illustrate a degradation effect of Bi doping on the thermoelectric properties of tetrahedrite in these synthesis conditions.

Enhancement of the spin Seebeck effect owing to bismuth substitution in thermoelectric generators fabricated from LPE Bi-substituted YIG films

Raising the thermoelectric voltage in spin thermoelectric generators is an important subject. We investigated the substitution of bismuth for yttrium to increase spin pumping at the paramagnetic metal and ferrimagnetic insulator (PM/FMI) interface, and tested bismuth-substituted iron garnet films grown by liquid phase epitaxy. Epitaxial Bi-substituted iron garnet films exhibit large growth-induced magnetic anisotropy perpendicular to the film surface. This anisotropy increases the magnetic damping α in the FMI; α also increases with increasing Bi content. We report the rise in voltage observed in a spin thermoelectric generator incorporating Bi-substituted YIG films grown by liquid phase epitaxy, and explain the origin of the voltage rise based on the results of FMR measurements.

The main role of bismuth in controlling linear and nonlinear optical, electronic and electrical parameters of Se–Ge–Bi thin films

A widespread analysis of the structural, optical, electronic and electrical properties of Se80Ge20-xBix with (x = 0, 5, 10, 15 and 20 at.%) glasses were carried out. The bulk materials of the studied films have been prepared utilizing the usual melt quench procedure. Thus, the thin film has been deposited under a vacuum of 10–5 Torr on cleaned glass substrates by thermal evaporation. The supreme purpose of this research is to highlight the role of adding bismuth to the films studied as a regulator and controller for the linear and nonlinear parameters. The thickness of the studied thin films has been mathematically determined by the methods of Swanepoel. Using logarithmic functions, it has been proven that the electron transport mechanism between the valence and conduction bands is an allowed indirect transition. Linear optical parameters, dielectric constants and also dispersion parameters have been calculated. The energy-loss functions (VELF and SELF) were discussed. The effect of Bi concentration in the studied thin films on the linear and nonlinear optical properties is determined based on the optical measurements (transmittance and reflectance spectra). The optical bandgap decreases with increasing Bi concentration; while the tail energy portrays an opposite behavior. Linear optical and electrical parameters are found significantly affected by the change of Bi concentration. In contrast, the nonlinear optical parameters have been computed utilizing (H. Ticha and L. Tichy) and Boling formula. Energies of Plasmon, Penn and Fermi and the electronic polarizability have been determined. Furthermore, the DC electrical conductivity has been studied as a function of both temperature in the thermal range from 300 to 500 K and also Bi concentration. In the extended and hopping regions, the activation energy and pre-exponential factor were extracted from the slopes and intercepts of straight lines. It has been found that increasing Bi content is controlled the electrical parameters and reduces the activation energies in the regions of the extended and the hopping states.

Role of Bi chemical pressure on electrical properties of BiFeO3–BaTiO3–based ceramics

Effect of Bi non-stoichiometry is one of the big issues in BiFeO3-BaTiO3 (BF-BT) ceramics that have not been resolved clearly. Therefore, 0.65Bi1+xFeO3-0.35BaTiO3 (x = 0–0.06) ceramics were synthesized by a conventional solid-state reaction at different sintering temperatures (TS) to control the Bi non-stoichiometry, which can be varied by the sublimation and/or evaporation of Bi+3 ions during sintering process. The effects of Bi chemical pressure on crystalline phase, microstructure, dielectrics, and piezoelectric properties of BF-BT were evaluated. X-rays diffraction revealed a single perovskite structure with pseudo-cubic symmetry. A prominent enhancement was noticed at x = 0.05 in ferroelectric, dielectric and piezoelectric properties. Typical ferroelectric behaviors were obtained, while unipolar and bipolar strains were enhanced with increasing Bi content. The maximum piezoelectric properties were found at TS = 1000 °C with x = 0.05, having d∗33 = 270 pm/V at 5 kV/mm with Curie Temperature (TC) = 432 °C.

Microstructural evolution and mechanical properties of binary Mg–xBi (x = 2, 5, and 8 wt%) alloys

Abstract The microstructures and mechanical properties of Mg–xBi (x = 2, 5, and 8 wt%) were investigated compared with pure Mg. The as-cast Mg–Bi billets consist of dendritic α-Mg grain matrix, divorced eutectic Mg3Bi2 phase and secondary precipitated Mg3Bi2 phase. After homogenization, secondary precipitated Mg3Bi2 particles were all dissolved into the matrix, while most of the divorced eutectic Mg3Bi2 intermetallic compounds retained. All the as-extruded samples exhibit fully dynamic recrystallization (DRX) and the average grain size decreases and the amount of nano-scale Mg3Bi2 precipitates increases with increasing Bi content. Additionally, Bi alloying has little influence on the texture of the as-extruded pure Mg, with all the samples showing typical basal texture. As the results of grain refinement and precipitation hardening, the strengths of the as-extruded samples increase under both tensile and compressive tests. Besides, the yield asymmetry significantly decreases with Bi content. Moreover, all the as-extruded samples represent similar ductility under compression, while the tensile elongation first increases and then decreases with more Bi added. The as-extruded Mg–5Bi alloy demonstrates good combination of strength and ductility. However, Mg–8Bi alloy displays lower tensile ductility than that of Mg–5Bi alloy due to the presence of abundant undissolved coarse Mg3Bi2 particles, which act as cracking sources during tensile test. Furthermore, the strain hardening rate Θ, strain hardening exponent n, and hardening capacity Hc are greatly reduced by Bi addition, mainly owing to the enhanced synergy effects of grain refinement and numerous Mg3Bi2 precipitates.