Hot Extrusion Research Articles

Impression creep behavior of extruded Mg–TiO2 composites prepared by powder metallurgy

Magnesium (Mg) composites with ceramic fillers are considered favorable for their recyclability compared to Mg alloys for lightweight designs with high creep resistance. In this work, we studied the difference in impression creep properties of pure magnesium and its composites, which contained 2, 3.5, and 5vol% of submicron TiO2 particles. For each composition, samples were fabricated by hot extrusion after hot pressing of the cold-compacted powders. Creep tests were conducted at temperatures in the 423–473K range and under stress levels in the 125–275MPa range. The results showed that the composites had higher creep resistance than pure magnesium, and increasing TiO2 content improved their creep behavior under all testing conditions. The effect of TiO2 content on grain size was statistically insignificant, and therefore, the improvement was attributed to reinforcing ceramic particles, which reduce the creep load on the magnesium matrix. The Dorn model was used in a new approach to calculate the effective stress on the magnesium matrix, justifying composites' higher creep load-bearing capacity than pure Mg under studied creep conditions. Fitting the Dorn exponential equation to creep data revealed that the stress exponent was between 6.6 and 8.6, and the activation energy was between 90.1 and 95.2kJ/mol for all compositions. Therefore, it was inferred that pipe diffusion-controlled dislocation climb was the creep mechanism for the studied materials.

Assessing processability of milled HME extrudates: Consolidating the effect of extrusion temperature, drug loading, and particle size via Non-dimensional cohesion

The downstream processability of Hot Melt Extrusion (HME) Amorphous Solid Dispersions (ASD), an underexplored topic of importance, was assessed through a multi-faceted particle engineering approach. Extrudates, comprised of griseofulvin (GF), a model poorly water-soluble drug, and hydroxypropyl cellulose (HPC), were prepared at four drug concentrations and three HME temperature profiles to yield cases with and without residual crystallinity and subsequently milled to five sieve cuts ranging from < 45 μm to 355 – 500 μm. Solid state characterization was performed with XRPD, FT-IR, and TGA. Particle scale properties of the milled extrudates were evaluated including particle size, density, surface energy, and morphologies imaged via SEM. It was observed that regardless of sieve cut size, drug concentration and HME conditions impacted the flowability trends, quantified via Flow Function Coefficient (FFC) and bulk density. As a novelty, the effects of various process parameters and drug loadings were consolidated into a dimensionless interparticle cohesion measure, granular Bond Number (Bog), to better correlate them with bulk powder properties. The significant contrast in particle morphologies, particle size, and densities among selected cases demonstrated that particle size alone should not be the sole consideration when correlating particle scale to bulk powder scale properties of milled extrudates. Instead, the HME temperature profile and ASD drug loading may be more suitable parameters affecting the bulk powder properties of the milled extrudates.

Effect of Precipitation Heat Treatment on a Mechanically Alloyed Al‐Based Composite Reinforced with Metallic Glassy Powder

An Al‐based composite reinforced with titanium‐based metallic glassy particles is synthesized by the powder metallurgy method through mechanical alloying followed by hot extrusion. The effect of precipitation heat treatment on the structure and properties of the composite is studied. During aging of the solution‐treated composite, crystallization of the metallic glassy reinforcement becomes more pronounced as the solutionizing temperature, solutionizing time, aging temperature, and aging time increase. A reaction layer has formed at the interface between the reinforcement and the matrix after the aging treatment. It is found that the addition of metallic glassy particles promotes precipitation of the nanophase in the matrix. With appropriate heat treatment, the compressive strength, yield strength, and fracture strain of the composite have increased to 942, 635 MPa, and 27%, respectively. Herein, it is demonstrated that the mechanical properties of these composites can be further enhanced through an appropriate heat treatment process, thereby having significant potential for a variety of industries, including aerospace, automotive, and defense, where high‐strength, lightweight materials are critical for performance and safety.

Roadmap for Power Generation of Industrial Hot Extruded Bi2Te3-Based Thermoelectric Device in Real-World Heat Sources.

Recovering waste heat through thermoelectric (TE) technology is critical for enhancing energy efficiency. However, commercial devices often require n- and p-type thermoelectric units to have similar cross-sectional areas and conductivities, complicating optimization of their figure of merit (ZT). Moreover, real-world heat sources are not constant temperature sources, and only heat flux can be measured. Given these constraints, selecting appropriate parameters for TE devices to maximize their output power for specific heat sources is of significant scientific and practical importance. In this work, we studied a series of n- and p-type Bi2Te3-based TE materials, prepared using commercial hot extrusion techniques, with average conductivities of approximately 650 S cm-1, 820 S cm-1, 1050 S cm-1, and 1300 S cm-1 over the temperature range of 50-250 °C. These materials were assembled into four different thermoelectric devices (HE1, HE2, HE3, and HE4). Finite element simulations for devices HE1, HE2, HE3, and HE4 (TE leg: 1.4 mm × 1.4 mm × 1.6 mm, device area: 40 mm × 40 mm) showed maximum power densities of 3953.5 W m-2 and 1300.8 W m-2 at 67,000 W m-2 and 33,500 W m-2 heat fluxes, respectively. The fabricated devices achieved maximum power densities of 2907.1, 3014.0, 2910.9, and 2525.4 W m-2 at 67,000 W m-2 heat flux, with discrepancies attributed to interface thermal resistance. Based on these findings, we have plotted output performance roadmaps for TE devices with different average electrical conductivities under various heat flux densities (67,000 W m-2 and 33,500 W m-2) as functions of external load and TE leg height. These roadmaps enable rapid design of TE devices tailored to specific external heat source conditions and cost requirements, thereby maximizing waste heat recovery. This study's use of electrical conductivity as a performance indicator for final device output power density offers direct guidance for practical waste heat recovery applications.

Improving Mechanical Properties of Chips-Based Aluminum Extrudates by Composite Hot Extrusion

Improving Mechanical Properties of Chips-Based Aluminum Extrudates by Composite Hot Extrusion

Characterization of different size reinforcement effects on microstructural failure mechanism in carbon nanotube-reinforced aluminum composites

In this study, we investigated the effect of reinforcement sizes on the tensile strength and ductility of carbon nanotube (CNT)-reinforced aluminum matrix composites fabricated through ball milling, followed by hot extrusion of a powder encapsulated in an aluminum container. We analyzed the microstructural properties of the samples, including the aluminum grain size, its spatial variation with the alignment of CNT, and CNT length. Nanoindentation test results revealed the spatial variation of hardness and Young’s modulus of composites with small-diameter CNTs, indicating local Al4C3 formation and interlock structure resulting from dislocation accumulation during the fabrication process. This explains dimples of different sizes observed on the fracture surfaces of the samples and the occurrence of CNT pullout. Furthermore, we proposed the failure mechanism of the composites under tensile strain and calculated the failure strain using the Whitehouse–Clyne model. The calculated failure strain agrees well with the experimental values. The high ductility of the composites is attributed to the large grain fracture and rotation of neighboring grains due to the constraint imposed by CNTs.

Amorphous solid dispersions of amphiphilic polymer excipients and indomethacin prepared by hot melt extrusion

Improving the solubility of poorly water-soluble drugs is essential for enhancing bioavailability, formulation flexibility and reducing patient-to-patient variability. The preparation of amorphous solid dispersions (ASDs) is an attractive strategy to formulate such drugs, leading to higher apparent water solubility and therefore higher bioavailability. For such ASDs, water-soluble polymer excipients, such as poly(vinyl pyrrolidone) (PVP) or poly(vinyl pyrrolidone-co-vinyl acetate) (P(VP-co-VA)), are employed to solubilize and stabilize the drug against crystallization. We posit that polymers bearing tertiary amides are particularly well suited to stabilizing drugs containing H-bond donors, as they offer strong H-bonding potential between the polymer and drug. The aim of this study was to compare new and established polymers with tertiary amides as excipients for ASDs. Experimental amphiphilic ABA triblock copolymers comprising poly(2-methyl-2-oxazoline) (pMeOx), poly(2-butyl-2-oxazoline) (pBuOx) and poly(2-butyl-2-oxazine) (pBuOzi) blocks, were compared with the established excipients, PVP and P(VP-co-VA). ASDs with indomethacin as the model drug were prepared at high drug loadings via hot melt extrusion. The extrudates were studied with DSC and PXRD, revealing the ASDs to be fully amorphous up to 75wt% indomethacin, independent of the polymer used. 13C CPMAS NMR provided insights into intermolecular associations as a function of drug loading, and suggested the presence of drug dimers at 75wt% drug loading in pMeOx-pBuOzi-pMeOx and pMeOx-pBuOx-pMeOx, which could affect physical stability. Independent of the polymers, the solid-state form of the drug in the ASD was found to affect the dissolution profile of the samples, insofar as the samples containing crystalline indomethacin showed slower dissolution than the fully amorphous ones. This study shows that the polymers comprising poly(2-oxazoline) and poly(2-oxazine) are effective polymers for ASD preparation, similar to PVP and P(VP-co-VA) which merits further investigations into these novel polymers for formulating ASDs.

Model-based real-time optimization in continuous pharmaceutical manufacturing

In this work, real-time optimization (RTO) schemes are proposed and applied on a continuous pharmaceutical manufacturing process which consists of three units: synthesis unit, hot melt extrusion unit and direct compaction line. The developed RTO strategies calculate the operating conditions by optimizing the considered objective functions while satisfying the specific constraints. Moreover, the RTO schemes can cope with intentional changes in the process and unintentional changes such as disturbances. Results from simulations and experiments are presented in this work. An advantageous performance is achieved when using the developed schemes.

In-situ synthesis and microstructural evolution of a SiC reinforced Al-50Si composite exhibiting exceptional thermal properties

Incorporating carbon nanotubes (CNTs) into Al-Si alloy to prepare in-situ SiC/Al-Si composites enhances thermal conductivity (TC) and reduces the coefficient of thermal expansion (CTE). However, challenges include CNTs aggregation and uneven SiC distribution. This study uses fluidized bed chemical vapor deposition (FBCVD) to achieve uniform CNTs coverage on Al-50Si powder. Subsequent powder hot extrusion and heat treatment above the eutectic temperature enable a gradual reaction between CNTs and Al/Si atoms, resulting in uniformly dispersed SiC within the SiC/Al-50Si composite. The formation mechanism of in-situ SiC particles and their impact on the microstructure, thermal and mechanical properties of the composite are further investigated. The formation process involves a two-step chemical reaction: lamellar Al4C3 phases transform into lamellar eutectic SiC + Al phases, which then transition into polyhedral SiC particles through epitaxial growth. This in-situ formation of SiC particles also impedes Si growth during heat treatment, refining Si particles and enhancing the composite’s properties. The resulting in-situ SiC/Al-50Si composite exhibits excellent thermal and mechanical properties, including a high TC of ∼162 Wm-1K−1, a low CTE of ∼ 8.7 × 10-6/K, and a good bending strength of approximately 253 MPa at room temperature.

Suppress defect-induced plastic instability to achieve superior strength-ductility combination of spray formed 7050 Al alloy

This research aimed to enhance the strength and ductility of spray formed (SFed) 7050 aluminum (Al) alloy through hot extrusion and subsequent heat treatment. Microstructure and mechanical properties evolution during these processes were investigated. It was found that the low densification of the SFed 7050 Al alloy due to various defects such as pores, with an average size of 7.6 μm and an area fraction of 3.7 % could be notably enhanced by hot extrusion, even achieving a level close to theoretical density. This process led to a transformation of grains from equiaxed to elongated shapes along extrusion direction and significant grain refinement, exhibiting a strong fiber texture. While the employed extrusion ratio exceeds 16 with proper heat treatment, the SFed 7050 Al alloys achieves superior strength-ductility combination compared with reported Al alloys. The achieved high performance should be attributed to the grain refinement, strong texture and high densification that suppress defect-induced plastic instability. Furthermore, the combination of hot extrusion and heat treatment, provides an effective way to enhance strength and ductility for SFed 7050 Al alloy.

Effect of grain size on mechanical characteristics and work-hardening behavior of fine-grained Mg-0.8Mn alloy via adjusting extrusion temperature

In this study, the Mg-0.8Mn (M08, wt%) alloy is subjected to hot extrusion at various temperatures ranging from 150 ℃ to 300 ℃, and the correlations between the microstructure evolution, tensile properties, and work hardening behavior at ambient temperature are elaborated. The M08 alloy extruded at 150 ℃ exhibits a bimodal microstructure, which included undynamic recrystallized (unDRXed) grains and fine dynamic recrystallized (DRXed) grains with an average size of 1.4 μm. As the extrusion temperature exceeds 210 °C, fully DRXed grains can be observed with grains growth becoming more pronounced with the increase of extrusion temperature. Notably, Mn atomic segregations are evident at the grain boundaries (GBs) in the M08 alloy extruded at 150 °C. It is also essential to highlight that the propensity for GB segregation is diminished with higher extrusion temperature, and the amount of α-Mn precipitates within grain interiors is increased in the M08 sample extruded at 300 ℃. An intriguing observation is the abnormal rise in yield strength (YS) with grain size as the extrusion temperature is increased. This phenomenon can be attributed to the diminishing effect of GB sliding and the concurrent enhancement of GB strengthening effect. However, as the extrusion temperature is raised from 150 °C to 300 °C, the ductility of M08 alloy experiences a substantial decline from 74 % ± 4–16 % ± 3 %. Meanwhile, the grain growth can bring about an increased strain hardening rate, which is primarily dependent on the transition in the dominant deformation mechanism from grain boundary sliding (GBS) to dislocation slip. This transition leads to a more substantial accumulation of dislocations within the coarser grains, thereby affecting the mechanical behavior of M08 alloy. This work provides valuable insights into the influence of extrusion temperature on the microstructure evolution and mechanical properties of Mg-0.8Mn alloy, offering a foundation for optimizing the processing parameters to achieve desired mechanical performance.

Fabrication and characterization of new hot extruded ZK60/CNTs+AgNPs nanocomposites for biomedical applications

Magnesium (Mg), with properties such as biodegradability and having a density and elasticity coefficient close to the bones of the body, has attracted a lot of attention as a serious option for orthopedic applications. However, the low compressive strength of Mg compared to the human bone and its weak antibacterial function limit its applications as a substitute for temporary implants to be used under load-bearing conditions. The aim of this paper is to evaluate the synergistic effect of CNTs + AgNPs nanofillers on the in vitro degradation, mechanical and antibacterial behavior of new ZK60/xCNTs + xAgNPs(x: 0, 0.25, 0.5, 1) composites made using semi powder metallurgy, followed by hot extrusion method. The ZK60/0.5CNTs+0.5 AgNPs (CA2) composite boasts a higher ultimate compressive strength (UCS) of 371 ± 15 MPa compared to 297 ± 6 MPa for ZK60 based alloys. The CA2 composite also exhibits a grain size of 9.8 μm and a microhardness of 81 HV.Also, the antibacterial activity assessment demonstrated that adding CNTs + AgNPs hybrid nanofillers to the Mg matrix could notably prevent growing and penetration of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), which indicates the synergy between antibacterial mechanisms of CNTs and AgNPs. Cytotoxicity studies confirm that composites with low amounts of CNTs + AgNPs did not show cytotoxic behavior against MG63 cells, although higher loading of CNTs + AgNPs caused toxicity. Also, the examination of osteogenic activity is consistent with other results. In general, according to the results, the potential application of CA2 composite for under load bearing implant application and bone infection treatment is proved.

Microstructure and Properties of 7050-T74 Aluminum Alloys with Different Zn/Mg Ratios

Aluminum alloy 7050-T74 with varying zinc-to-magnesium (Zn/Mg) mass fractions was synthesized using melt casting and hot extrusion techniques. This study investigated the influence of different Zn/Mg ratios on the microstructure, mechanical properties, and corrosion resistance of the alloy. Light microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), tensile testing, and corrosion testing were employed as analytical methods. The findings indicate that as the Zn/Mg ratio increases from 2.36 to 3.84, the proportion of low-angle boundaries (LABs) within the alloys initially rises and then decreases, achieving a balance between high strength and favorable elongation. Specifically, at a Zn/Mg ratio of 2.72, the alloy exhibits a tensile strength of 641 MPa, a yield strength of 609 MPa, and an elongation of 10.1%. Additionally, increasing the Zn/Mg ratio to 2.90 slightly reduces intergranular corrosion resistance while enhancing exfoliation corrosion resistance.

Phase Transformation, Microstructural Evolution and Tensile Properties of a TiH2-Based Powder Metallurgy Pure Titanium

Multiple phase transformations were carried out during dehydrogenation process of TiH2-based powder metallurgy. The influence of phase transformation on the microstructure is highly worthy of attention. In situ synchrotron radiation was employed to investigate the phase transformation sequence of TiH2 powder compact during the vacuum sintering process. It was found that a transformation route TiH1.971 → TiH2 + TiH + TiH0.71 + α(H) → TiH + TiH0.71 + α(H) → TiH + TiH0.71 + α(H) + β(H) → α(H) → α took place, resulting in an equiaxed microstructure. Increasing heating rate and avoiding the intense dehydrogenation to retain hydrogen-rich β (β(H)) and TiHx aciculae at the interfaces is found to be a feasible method to fabricate hierarchical α-Ti structures. A fully dense fine martensitic microstructure was produced after fast heating the TiH2 powder compact to 1100 °C and an immediate hot extrusion. Subsequently, by vacuum annealing treatment at 700 °C, composite α/βt lamellar structures were generated and a simultaneously enhanced tensile strength of 746 MPa and excellent elongation to fracture of 33.8% were achieved. It is suggested that adjusting the dehydrogenation reactions of TiH2-based powder metallurgy is conductive to generating hierarchical lamellar structures with a highly promising combination of strength and ductility for pure Ti.

Preparation and excellent mechanical properties of nanocrystalline GW103K Mg alloy by HDDR technology

Grain size of GW103K Mg alloy powder were markedly refined to about 45 nm from 20 μm by an optimized hydrogenation-disproportionation-desorption-recombination (HDDR) process. By changing temperature, hydrogen pressure and time, the optimum hydrogenation conditions are explored by orthogonal design. Then the complete dehydrogenation process was determined by using single factor control variables. Furtherly, the HDDRed powder was spark plasma sintering (SPS) sintered and hot extruded to prepare GW103K alloy bulk. XRD, OM, scanning electron microscopy (SEM), and transmission electron microscope (TEM) were used to analyze the phase transformation and microstructure evolution, based on which the grain refining mechanism during the HDDR were discussed. The optimum HDDR parameters for preparing nanocrystalline Mg alloy powders are hydriding at 550 °C under 5 MPa hydrogen pressure for 24 h and dehydriding at 550 °C for 8 h in vacuum. The nanocrystalline GW103 alloy presents a notable dimensional stability and the grain size of the alloy bulk is 43 nm after SPS and hot extrusion. As a result, the nanocrystalline GW103K specimens exhibit excellent mechanical properties compared to the coarse-grained counterparts. Especially, the nanocrystalline GW103K alloy has a tensile elongation of 21.1% which is much more than those of the as-cast and as-extrusion alloys.

Microstructure development and strengthening behaviour in hot-extruded Ti-Mo alloys with exceptional strength-ductility balance

A series of strong and ductile Ti-Mo alloys containing 2.5, 5, 7.5 and 10 wt% Mo was experimentally investigated by a two-stage blended-elemental powder metallurgy process. This process consisted of a spark plasma sintering stage for powder-consolidation and in-situ-homogenisation, and a hot extrusion stage for densification and microstructure enhancement. Microstructures in the extruded alloys changed from α dominant to β dominant with molybdenum addition. Simultaneously, a grain refinement effect was observed due to suppressed α precipitation and increase β retention. A significant strengthening effect was observed with molybdenum addition. In comparison with similarly processed commercially pure titanium, Ti-10Mo exhibited a yield strength improvement of 290 % to 1382.8 MPa, and an ultimate tensile strength improvement of 239 % to 1496.5 MPa. Meanwhile, Ti-5Mo exhibited a yield strength improvement of 211 % (1007.9 MPa) without any substantial reduction in ductility, resulting in an exceptional tensile toughness of 361.3 MJ.m−3. A quantitative analysis of strengthening mechanisms reveals considerable strengthening effects from solid solution strengthening, dislocation strengthening, and grain refinement effects. These factors arise from the novel multi-modal microstructures formed by thermomechanical processing at super-transus temperatures. The newly achieved balance of strength and ductility appears to be unrivalled amongst all previously reported binary Ti-Mo alloys.

Bimodal grain structure, phase transformation, and mechanical properties of a Mg-Gd-Y-Zn-Zr alloy during hot extrusion

In this study, we investigated the evolution of grain structures and second phases of a Mg-9.5Gd-4Y–2Zn-0.3Zr alloy during two-stage deformation that took place in the metal during hot extrusion, as well as their effects on its mechanical properties. We found that the alloy exhibited a bimodal grain structure consisting of equiaxed dynamic recrystallized (DRXed) grains and elongated unDRXed grains. As the extrusion process progressed, DRX occurred on a large scale, resulting in an increase in the proportion of DRXed grains from 17.8% to 93.2%, and a reduction in average grain size from 80.3 μm to 9.41 μm. The grain orientation also underwent a transition from a single orientation of an extrusion direction (ED) parallel to <0001> (i.e. ED//<0001>) to mixed orientations of ED//<01–10> and ED//<0001>. The primary mechanism of dynamic recrystallization (DRX) during extrusion involved particle-stimulated nucleation (PSN) accompanied by both continuous and discontinuous DRX. The Mg-9.5Gd-4Y–2Zn-0.3Zr alloy mainly contained intergranular 18R-long period stacking order (LPSO) phases and intragranular 14H-LPSO. As the extrusion process progressed, 18R-LPSO changed from blocky to lamellar to accommodate deformation, and β-Mg5(Gd,Y) phase particles dynamically precipitated along DRXed grain boundaries. The 14H-LPSO phase was found to be primarily distributed within coarse unDRXed grains. As deformation via extrusion progressed, the quantity of 14H-LPSO gradually decreased. Ultimately, with the gradual dissolution of Mg5(Gd,Y), 14H-LPSO reprecipitated within the recrystallized grain boundaries. As the extrusion process progressed, both the yield strength (YS) and elongation (EL) increased from 132.6 MPa to 287.6 MPa and from 10.8% to 15.5%, respectively. This was mainly attributed to the significant reduction in grain size and second phase size.

Melt-extruded formulations of fenofibrate with various grades of hydrogenated phospholipid exhibit promising in-vitro biopharmaceutical behavior

In the current study, it was demonstrated that three commercially available grades of hydrogenated phospholipids (HPL) differing in their content of phosphatidylcholine may be used as components for hot melt-extruded binary (HPL as sole excipient) or ternary (in combination with copovidone) solid dispersions of fenofibrate (FEN) at mass fractions between 0.5 and 20% (ternary) or 80% (binary). X-ray powder diffraction indicated complete conversion of crystalline fenofibrate into the amorphous state by hot melt extrusion for all ternary blends. In contrast, both the binary blends (HPL- and copovidone-based) contained minor remaining crystallites. Irrespectively, all solid dispersions induced during dissolution studies a supersaturated state of FEN, where the ternary ASDs showed enhanced and more complete release of FEN as compared to the binary blends and, even more pronounced, in comparison to the marketed micronized and nano-milled formulations. In terms of the cumulated amount permeated, there were marginal differences between the various formulations when combined dissolution/permeation was done using FeSSIF as donor medium; with FaSSIF as donor medium, the binary HPL-ASD containing the grade with the highest phosphatidylcholine fraction performed best in terms of permeation, even significantly better than the marketed nano-crystal formulation. Otherwise, no significant differences were seen between the various grades of HPL when FEN dissolution and permeation were analyzed for ternary solid dispersions. In conclusion, the in-vitro biopharmaceutical behaviour of hydrogenated phospholipid-containing blends manufactured by hot melt extrusion appears promising. They can be a viable formulation option for poorly water-soluble and lipophilic drug compounds like FEN.

An in vitro and in vivo study of biodegradable Zn–Cu–Li alloy with high strength and ductility fabricated by hot extrusion combined with room-temperature ECAP

Deformation processing is a commonly used strategy to improve the microstructure and hence mechanical properties of biodegradable Zn alloys. However, a single conventional processing method is usually limited in achieving this goal. In this work, hot extrusion combined with room-temperature equal channel angular pressing (ECAP) was used to fabricate biodegradable Zn–Cu–Li alloy. Compared to the hot-extruded alloy, the further ECAPed alloys have significantly finer Zn grains and precipitate more submicron- and nano-sized ε-CuZn4 particles. Moreover, the 4-pass as-ECAPed alloy exhibits the best comprehensive mechanical properties with yield strength of 315 ± 3 MPa, ultimate tensile strength of 444 ± 13 MPa and elongation of 81 ± 5%, which are 13.3%, 38.8% and 72.3% higher than those of the hot-extruded alloy, respectively. In addition, in vitro and in vivo tests were performed on the 4-pass as-ECAPed alloy to evaluate its corrosion behavior, antibacterial property, cytotoxicity and biocompatibility. In vitro results showed that the 4-pass as-ECAPed alloy exhibits better corrosion resistance than the 8-pass alloy. Also, it shows good antibacterial property, hemocompatibility and cytocompatibility. In vivo results demonstrated that the 4-pass as-ECAPed alloy exhibits faster and more uniform degradation than the pure Zn (as a control group). Both the pure Zn and 4-pass as-ECAPed alloy promote formation of new bone, the mass of which increases over time. The 4-pass as-ECAPed alloy shows slightly weaker osteogenic capacity but better overall osteointegration than the pure Zn. Furthermore, both the pure Zn and 4-pass as-ECAPed alloy exhibit good in vivo biosafety.

Review of Solid-State Consolidation Processing Techniques of ODS Steels (Hot Extrusion, Hot Isostatic Pressing, Spark Plasma Sintering, and Stir Friction Consolidation): Resulting Microstructures and Mechanical Properties

Review of Solid-State Consolidation Processing Techniques of ODS Steels (Hot Extrusion, Hot Isostatic Pressing, Spark Plasma Sintering, and Stir Friction Consolidation): Resulting Microstructures and Mechanical Properties