Microstructure, Plasticity and Ductility of a TNM+ Alloy Densified by Spark Plasma Sintering

Abstract

This work presents a study of the microstructure and mechanical properties of a TNM+ alloy (Ti-43.5Al-4Nb-1Mo-0.1B-0.3C-0.3Si, in at.%) densified by Spark Plasma Sintering (SPS), in comparison to the as-SPSed TNM alloy, which contains neither carbon nor silicon. Tensile tests at room temperature and 800 °C, as well as creep tests at 800 °C and 200 MPa, were performed. The microstructures and the fracture surfaces of deformed samples were studied by scanning and transmission electron microscopies, as well as by X-ray diffraction. The deformation mechanisms were investigated by means of in situ straining experiments and post-mortem analyses of deformed samples, both performed by transmission electron microscopy. Contrary to the TNM alloy, the as-SPSed microstructure of the TNM+ alloy does not contain β/βo phase due to the incorporation of carbon. At room temperature, the TNM+ alloy exhibits a yield stress of 520 MPa but a poor ductility of less than 0.1% of plastic strain. The incorporation of carbon and silicon leads to an increase in the creep resistance of the alloy at 800 °C. Despite the fact that iron inclusions are responsible for the premature failure of some samples during tensile tests, the TNM+ alloy is found to be able to deform plastically at room temperature by the glide of ordinary dislocations and by twinning.

Compactability Regularities Observed during Cold Uniaxial Pressing of Layered Powder Green Samples Based on Ti-Al-Nb-Mo-B and Ti-B

“…(2) An experimental method has been proposed to ascertain the relationship between the degree of deformation and the relative density of powder green samples in relation to compaction pressure and the duration of pressure application. This method applies to single-layer, double-layer, and multilayer materials based on Ti-B- (20,30,40) wt % Ti and TNM (at %: 51.85Ti-43Al-4Nb-1Mo-0.15B). (3) Rheological patterns were studied during cold uniaxial pressing of powder green samples depending on the composition of the initial components, height, and number of layers Ti-B- (20,30,40) wt % Ti and TNM (at %: 51.85Ti-43Al-4Nb-1Mo-0.15B).…”

“…This method applies to single-layer, double-layer, and multilayer materials based on Ti-B- (20,30,40) wt % Ti and TNM (at %: 51.85Ti-43Al-4Nb-1Mo-0.15B). (3) Rheological patterns were studied during cold uniaxial pressing of powder green samples depending on the composition of the initial components, height, and number of layers Ti-B- (20,30,40) wt % Ti and TNM (at %: 51.85Ti-43Al-4Nb-1Mo-0.15B). Layers were selected containing both 100 vol % TiB and TNM, and the following proportions: 70TiB/30TNM, 50TiB/50TNM, 30TiB/70TNM.…”

“…Powder metallurgy methods serve as the primary technologies for manufacturing composite materials. These methods encompass various techniques, including selective laser sintering [31][32][33][34][35], hot isostatic pressing [36][37][38], spark plasma sintering [39][40][41][42], selfpropagating high-temperature synthesis (SHS) [43][44][45][46], and several other methods [47][48][49][50], wherein pressed powder green samples serve as precursors. The quality of the green sample, which encompasses factors like uniform density along its height and radius, relative density across the entire batch, and technological strength, significantly influences the physical, mechanical, and operational properties of the resulting products.…”