We establish a methodology of in-situ dual-deoxidation to fabricate advanced titanium matrix composites (TMCs) by pressureless sintering (PLS). Specifically, the in-situ dual-deoxidation of impurity O in Ti matrix was designed as the in-situ formation of H2O and La2O3 particles, which was accomplished by PLS of advanced TMCs from powder mixtures containing Ti–6Al–4V matrix of TiH2 and 60Al40V together with LaB6 addition. Interestingly, the advanced TMCs with in-situ La2O3 particle and TiB whisker have various merits, including the significantly reduced O content in the Ti matrix, the refined equiaxed α-Ti grain with monolayer nanosized L phase grain boundary, and especially the nearly full-density evading Kirkendall's pore. Resultantly, the advanced TMCs circumvent the strength–ductility trade-off of representative Ti–6Al–4V TMCs by various materials processing methods. Our results provide a novel strategy for fabricating cost-effective advanced TMCs by PLS to yield superior mechanical properties. 

In-situ dual-deoxidation design of advanced titanium matrix composites by pressureless sintering

Porous boron-doped diamond for efficient electrocatalytic elimination of azo dye Orange G

In the present study, 98.6–99.5% dense in situ reinforced Ti6Al4V/TiB composites were manufactured with a newly developed approach based on hydrogen-assisted blended elemental powder metallurgy (BEPM). The approach includes the activation milling of titanium powder produced with hydrogenation-dehydrogenation (HDH-Ti powder) with finer TiB2 additives, following blending with TiH2 and master alloy (MA) powders, and final press-and-sinter operations. Scanning electron microscope (SEM) observations prove the formation of microstructures with improved density and homogeneous distribution of TiB reinforcements in a sintered Ti6Al4V matrix. Hardness and compressive tests validated the high mechanical characteristics of produced composites. The effect of preliminary milling time over 2–6 h and the ratio of hydrogenated and non-hydrogenated titanium powders used (TiH2 vs. HDH Ti) on microstructure and mechanical properties were studied to further optimize the processing parameters. Test results indicate the above approach can be regarded as a promising route for the cost-effective manufacturing of Ti6Al4V/TiB composite with reduced porosity, tailored microstructure uniformity, acceptable impurity level and, hence, mechanical characteristics sufficient for practice applications.

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In Situ Ti6Al4V/TiB Composites Prepared by Hydrogen-Assisted Sintering of Blends Containing TiH2 and Ball-Milled Ti+TiB2 Powders

The surface treatment of Ti80 alloy with different microstructures was performed by laser shock peening (LSP), and the effect of LSP on Ti80 alloy on microstructure and corrosion properties was investigated. After LSP, the surface grains of Ti80 alloy with different microstructures were all refined, microhardness was significantly increased, and compressive residual stress was generated, and both microhardness and compressive residual stress showed gradient change characteristics along the layer depth. The corrosion resistance of Ti80 alloy with different microstructures was improved in both 3.5% NaCl solution and 5MHCL solution after LSP. Before LSP, the corrosion resistance of lamellar microstructure was the best, followed by bimodal microstructure and the worst by equiaxial microstructure, while the corrosion resistance of equiaxial microstructure exceeded that of bimodal microstructure under the combined effect of volume fraction of β phase, thickness of α phase and compressive residual stress after LSP. 

Effect of laser shock peening on the corrosion properties of Ti-6Al-3Nb-2Zr-1Mo alloy

Effect of Master Alloys on Synthesis and Mechanical Properties of Ti-6Al-4V Alloy Produced by Elemental Powder Blends

Comparative study on the densification process of different titanium powders

Ti80 (Ti-6Al-3Nb-2Zr-1Mo) is a recently developed near-α titanium alloy that is generally applied in marine applications. In this study, the feasibility of producing the Ti80 alloy via the blended elemental powder metallurgy (BEPM) press-and-sinter method was demonstrated. Generally, the presence of elements with low diffusion mobility in titanium (Mo, Nb) creates difficulties with diffusion-controlled healing of the porosity and the realization of microstructural uniformity. These issues were minimized by using titanium hydride powder instead of titanium powder to activate the sintering, as well as by the proper selection of complex alloying powders rather than elemental powders to promote alloy uniformity. The time-temperature conditions to obtain a chemically and microstructurally homogeneous and nearly-dense alloy microstructure were determined. Special attention was given to the microstructural peculiarities of the sintered material to regulate its mechanical characteristics. Finally, the processing parameters were determined to reach the properties required by alloy specifications. This enabled both the fully beta transformed lamellar microstructure inherent to beta phase field sintering and one that could be modified via post sintering thermomechanical processing.

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Microstructure and Properties of Ti80 Alloy Fabricated by Hydrogen- Assisted Blended Elemental Powder Metallurgy

Titanium is widely used in the fields of medicine, industry, and biological science due to its excellent properties. In addition, titanium powder metallurgy (PM) is widely used in production becaus...

Peng Lei

Papers

Comparative study on the densification process of different titanium powders

Microstructure and Properties of Ti80 Alloy Fabricated by Hydrogen- Assisted Blended Elemental Powder Metallurgy

Evaluation and parameter analysis of compaction equations applied to titanium powder