Papers by Author: Zhi Guang Liu

Abstract: A novel biocomposite Ti-35wt%Nb-2.5wt%Sn-15wt%HA powders was synthesized by high energy ball mill(HEBM) for various periods of time. The microstructure and characteristics of the milled powder particles were investigated. Results showed that in the composite powders milled for 4h, Ti was still exhibited primary α phase, with the increase of ball milling time up to 8h, Ti transformed into primary β phase and a little α phase, after ball milling for 12h, Ti transformed into β phase fully. the transform temperature was 380.06°C. And TEM and PSD results indicated that nanostructure was obtained after 12h milling..

Abstract: A near-α high temperature titanium alloy, Ti-6Al-2.5Sn-4Zr-0.7Mo-0.30Si, was produced with various Y contents from 0 to 0.7wt% by arc-melting technique to study the influence of Y on its microstructure and mechanical properties. It was found that small amount of Y obviously refines the grain size of Ti-6Al-2.5Sn-4Zr-0.7Mo-0.30Si alloy. SEM and TEM observations revealed that Y-containing phase precipitated at the β grain boundary in the form of Y2O3 particles. Hardness and compression tests performed at room temperature revealed the strengthening effect of Y.

Abstract: In the present study, we tried to make Ti matrix/hydroxyapatite biocomposites using powder metallurgy and chemical treatments. Three composites were produced: Ti-30vol%HA, Ti15Mo-30vol%HA and Ti13Nb13Zr-44vol%HA. After mechanical milling and spark plasma sintering, Ti/HA composite compacts were produced. Microstructure observations and mechanical property tests showed that composites with two components (Ti-HA) have high hardness, moderate compress strength and lower density. The produced Ti/HA bulk composites were subjected to chemical treatment of immersion into phosphoric acid solution and porous structure was obtained. The obtained porous structure was characterized.

Abstract: In this paper, a rapid solidification (RS) method was employed to produce yttrium-containing TiAl based alloy ribbons. The microstructure evolution was investigated in terms of yttrium addition and RS parameters. For comparison, the conventionally cast counterpart alloys were studied as well. It was found that the microstructure of as cast alloys is sensitive to the Y content. The alloys with addition of 0 to 1.0at.% Y were of lamellar microstructures, but the alloy samples with 1.5 and 2.0at.% Y additioin were of strip-like microstructure. The yttrium-free alloy exhibited full γ phase, while the Y-bearing alloys contain γ phase, a small amount of α2, and yttrium containing phases. With increasing Y content, the secondary dendritic arm spacing (SDAS) gradually reduced. In the case of the rapidly solidified alloys, the microstructure was refined evidently when compared with the as cast counterparts. The fine Y-rich precipitates were homogeneously distributed in the matrix with a particle size of several tens of nanometers. A bcc phase (a=0.314 nm) was found in the alloys containing more than 1.5at.% Y, which was attributed to the extension of the solubility of Y in the matrix by rapid solidification.