Effect of starting powder grade on sintering and properties of PM titanium metal matrix composites

Abstract

The attractive physical and mechanical properties that can be obtained with Ti metal matrix composites (Ti-MMCs), such as high specific modulus, strength or wear resistance have been documented extensively. Interest in MMCs for use in the automotive industries, aerospace, and other structural applications has increased over the past 25 years as a result of several processing routes being developed and availability of reinforcements. Additionally, Ti powder metallurgy offers the possibility of creating net shape or near net shape parts without the material loss and cost associated with machining intricate components from wrought stock material, Ti being notoriously difficult to machine. This work focuses on research of a suitable Ti based metal matrix which will be reinforced by particles. First an adequate sintering assembly was designed and studied. Next, in order to achieve desired levels of mechanical properties, different Ti powders (either pure Ti or Ti hydride) were tested as metal matrix. These compacts were handled in different atmospheres (Ar and air) and compacted at different pressures followed by sintering at different conditions (temperature, time). Characterisation of the samples included hardness, density, oxygen content and microstructural analysis. This showed the influence of impurities in the raw powder as well as of the powder size and the processing parameters. Finally after the characterisation results, the two most suitable starting powders were selected for the fabrication of the Ti-MMCs. Such Ti based matrices have been reinforced with particles (TiB 2 ) at varying contents. Conclusively, the characterisation results of the compacted Ti based composites showed the importance of the adequate selection of the starting powder and the processing parameters simultaneously to achieve the desirable levels of mechanical properties for the Ti based composites.

Interstitial elements in Ti–13Nb–13Zr alloy produced by powder metallurgy using hydride powders

“…During sintering, due to the high solubility of oxygen in titanium at elevated temperatures, the oxide layer dissolves interstitially into the lattice of titanium. For that reason, oxygen content in PM titanium components is mainly attributed to the levels in the starting powders 8,16. In this work, this is verified by the increase of 83% in oxygen levels with the reduction in approximately a quarter of the mean particle size (Table 5).…”

“…For that reason, oxygen content in PM titanium components is mainly attributed to the levels in the starting powders. 8,16 In this work, this is verified by the increase of 83% in oxygen levels with the reduction in approximately a quarter of the mean particle size (Table 5).…”

Effect of Surface Finish on TiO2 Films Obtained Thermally as Corrosion Protection

“…Titanium and its alloys are materials widely used in industrial applications (1,2) and biomedical applications because they are a biocompatible material with good resistance to corrosion. The most used titanium alloy is Ti6Al4V, since this alloy has a biphasic structure (α + β) which has good mechanical properties and resistance to corrosion (3).…”