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High oxygen Ti6Al4V alloys are fabricated by vacuum sintering and hot rolling using hydrogenation-dehydrogenation Ti6Al4V powder and ZrO2 powder as raw materials. The complete dissolution of oxygen and zirconium atoms results in an increase in lattice constant and strength. As-rolled Ti64-ZrO2 sample exhibits a bimodal structure with a fine acicular α phase of around 1 μm. Ti64-0.75 ZrO2 alloy with equivalent oxygen content close to 0.6 wt.-% presents a good combination of the high tensile strength (1180.2 MPa) and sufficient elongation (7.3%). Therefore, the critical oxygen content for the ductile-to-brittle transition of powder metallurgy Ti6Al4V alloy can be improved by suitable preparation methods. The formation of a fine β transformation structure may be one of the reasons for maintaining sufficient ductility. [ABSTRACT FROM AUTHOR]

In this study, phosphorus-containing Fe-5 wt.% Si silicon steel sheet was prepared by powder loose sintering followed by hot rolling. Defect-free sheet with high P content was achieved. The study found that P effects on sintering promotion and processing deterioration were significantly suppressed by the presence of Si in steel. Appropriate P content would significantly improve the mechanical and magnetic properties of the sample. Under a comprehensive consideration, P content of 0.3-0.5 wt.% was suitable for silicon steel. Compared with P-free silicon steel, with 0.3 wt.% P addition, the tensile strength of silicon steel increased from 521 MPa to 680 MPa. As to the magnetic performance, the sample with 0.5 wt.% P had B8 of 1370.5 mT, and W10/50 0f 1.16 W·kg−1, while those for P-free sample were 1332.3 mT, and 1.46 W·kg−1, respectively. FeP phase with special morphology would be precipitated in samples with P addition. [ABSTRACT FROM AUTHOR]

Simultaneous improvement of both the strength and electrical conductivity of Cu–Fe alloys (CFAs) through the conventional casting method is an extremely challenging task. In this study, an attempt was made to overcome this issue via preparing CFAs with ultrafine alloy powders embedded with nano Fe particles. Ultrafine CFA powders with various Fe contents ranging from 5 to 50 wt.% were synthesized by a novel rapid solidification route, namely, gas–water combined atomization (GWA) process. The alloy powders prepared via GWA were then processed by pressureless sintering, hot rolling, annealing, and cold rolling. The microstructure evolution, mechanical properties, and electrical conductivity of CFAs were comprehensively investigated. The average size of Cu grain and Fe particles in all sintered CFAs was smaller than 3 and 2 μm, respectively. The grains of sintered CFAs were obviously refined by the Fe particles, and the addition of Fe inhibited the formation of Cu twins. After rolling, the Fe particles elongated and became fibrous along the rolling direction. The degree of formation of fibrous Fe enhanced with the increase of Fe content. Cold-rolled CFAs with 5–50 wt% Fe exhibited the tensile strength of 560–1250 MPa and conductivity of 33–65% IACS, indicating that CFAs in this study achieved superior mechanical and electrical properties. The microstructure evolution and strengthening mechanisms of CFAs were described. These findings can provide new insights into the powder metallurgy manufacturing of high-performance CFAs. • Ultrafine CFA powders were prepared by gas-water combined atomization. • The average size of Fe particles and grains of sintered CFAs was 2–3 μm. • Cold-rolled CFAs achieved superior mechanical and electrical properties. [ABSTRACT FROM AUTHOR]

High-plasticity in-situ TiB/Ti matrix composites (TMCs) are fabricated by in-situ reaction between Ti and ZrB 2 powder during vacuum sintering followed by hot rolling. Uniform microstructure is observed in the TMCs with obvious grain refinement. Compared with pure titanium, the mean grain size of Ti-2.0 wt% ZrB 2 composite significantly decreases from 50.7 µm to 17.5 µm, decreasing by 65%. Accordingly, Ti-2.0 ZrB 2 composite displays outstanding mechanical properties of 734.6 MPa in ultimate tensile strength, 579.0 MPa in yield strength, 21.4% in elongation, while these values of pure Ti are 632.4 MPa, 507.0 MPa, and 14.2%, respectively. The strength improvement of TMCs can be mainly attributed to five parts: grain refinement, solid solution strengthening, load transfer mechanism, CTE mismatch between TiB and Ti matrix and the dislocation substructure hardening. Among them, dislocation substructure hardening (more than 50% of the total improvement) takes the dominant position in strength increment in the as-rolled TiB/Ti matrix composites. [Display omitted] • In-situ TiB/Ti composites were synthesized by ZrB 2 additive via PM process. • Obvious grain refinement is found with grain size decreasing from 51 µm to 16 µm. • TiB/Ti composites show a balanced combination of good strength and high ductility. • Ti-2 wt% ZrB 2 sample has UTS of 734 MPa, YS of 579 MPa and EL. of 21%. • Strength increment caused by dislocation substructure hardening is ranged from 47.2 MPa to 116.6 MPa. [ABSTRACT FROM AUTHOR]

• High-plasticity PM Ti material with high O content is prepared with ZrO 2 addition. • The strength-ductility trade-off dilemma of PM titanium alloy is broken. • Ti-1.0 wt% ZrO 2 sample (0.56 wt% O) has UTS of 824 MPa and EL. of 15%. • Zr and O atoms fully dissolve in the Ti matrix, leading to lattice constant change. • The strengthen effect of ZrO 2 is calculated as 146.7 MPa/wt% ZrO 2. [Display omitted] High-plasticity titanium materials with high oxygen content were prepared by powder metallurgy (PM) and hot rolling, using pure Ti and ZrO 2 powder as raw materials. Completely dissolved oxygen and zirconium atoms resulted in the lattice constant change, thereby increasing the strength. Although the oxygen content was up to 0.56 wt% (much higher than the oxygen threshold of 0.33 wt%), PM Ti still exhibited high plasticity. The Ti-0.5 wt% ZrO 2 sample (0.43 wt% O) had UTS of 737 MPa and EL. of 28%, while the Ti-1.0 wt% ZrO 2 sample (0.56 wt% O) had UTS of 824 MPa and EL. of 15%. Compared to pure Ti, the addition of 0.5 wt% ZrO 2 resulted in a noticeable increase in UTS (increased by 9%) and EL. (increased by 19%). The strength-ductility trade-off dilemma of PM Ti alloy was broken. The formation of fine and equiaxed dynamic recrystallized grains may be one of the reasons that increased the ductility. The reinforcement effect of ZrO 2 was calculated as 146.7 MPa/wt% ZrO 2. [ABSTRACT FROM AUTHOR]

Microstructure and mechanical properties of two kinds of oxide dispersion strengthened concentrated solid solution alloys (CSAs), FeCoNi-1.5Y 2 O 3 (FCNY) and FeCoNi-1.2Ti-1.5Y 2 O 3 (FCNTY), are studied through a comparing investigation with FeCoNi (FCN) CSAs. All these alloys are fabricated by mechanical alloying, spark plasma sintering, hot rolling and annealing treatment. For three kinds of alloys, both the as-milled powders and bulk materials are of single face-centered cubic structure. Electron backscattered diffraction results reveal that the texture transformation is suppressed during the hot rolling process because the movement of grain boundaries is hindered by the oxide particles. Compared with FCN CSAs, grains are refined by 43% and 47% for FCNY and FCNTY CSAs, respectively. Nano-sized Y 2 O 3 (monoclinic structure) and Y 2 Ti 2 O 7 (pyrochlore structure) particles are uniformly distributed in FCNY and FCNTY CSAs, respectively. Both Y 2 O 3 and Y 2 Ti 2 O 7 particles show a semi-coherent relationship with the matrix. Yield strength of FCN, FCNY and FCNTY CSAs is 559, 981 and 1050 MPa, respectively. Theoretical calculations illustrate that high strength of FCNY and FCNTY CSAs comes from refined grains and high-density nano-sized oxide particles. • Nano-sized Y 2 O 3 and Y 2 Ti 2 O 7 particles were introduced into FeCoNi based concentrated solid solution alloys (CSAs). • Average size, crystal structure and orientation relationship of Y 2 O 3 and Y 2 Ti 2 O 7 particles were analyzed. • Hot rolling may promote the "cubic → monoclinic" phase transition of Y 2 O 3 particles in FeCoNi-1.5Y 2 O 3 CSAs. • Enhanced strength in ODS-FeCoNi CSAs originates from the refined grains and high-density nano-sized oxide particles. [ABSTRACT FROM AUTHOR]