Investigations on the consolidation of TNM powder by admixing different elemental powders

Abstract

In the conventional powder metallurgy (PM) process route, finished components are produced from metallic powder materials by pressing at room temperature followed by pressureless sintering in a furnace. This simple method for fast and cost-effective processing is not suitable for γ-based titanium aluminides. Due to their brittleness, these cannot be compacted in the conventional way. In order to qualify this group of alloys for the PM route, a possible solution is the addition of elemental titanium or aluminum powder. In this study, the basis is commercially available pre-alloyed TiAl44-4Nb-0.7Mo-0.1B (TNM) powder with high application potential for example in the aerospace industry. Investigations are carried out to determine the influence of different admixtures of elemental powders on the compaction result and the resulting mechanical properties. The TNM powder is mixed with pure titanium and aluminum powders and pressed to a compact using graphite as tool lubricant. The results show that the admixture of elemental powders enables the consolidation of TNM powder. However, depending on the load applied, a certain minimum proportion of the respective elemental powder is necessary to produce a compact. Furthermore, a significant influence on the relative density as well as the strength of the pressed product can be observed.

Pressing and Sintering of Titanium Aluminide Powder after Ball Milling in Silane-Doped Atmosphere

“…In order to characterise and quantify the mechanical green properties, the splitting tensile strength was determined. This strength test is used for brittle materials [28]. For this purpose, the samples were clamped in a force test rig and radially loaded until the sample broke (see Figure 2).…”