Strengthening behaviour and mechanisms of extruded powder metallurgy pure Ti materials reinforced with ubiquitous light elements

Abstract

Ubiquitous light elements (ULEs) like oxygen (O), nitrogen (N), carbon (C) and hydrogen (H) can be the key additive elements to achieve the high specific strength and cost-effectiveness of powder metallurgy (PM) titanium (Ti) materials. They have high potential to be employed as promising useful reinforcements of conventional expensive alloying elements like vanadium (V) and Niobium (Nb). In this study, two ULEs, oxygen and hydrogen, were induced into pure Ti matrix via the PM route, and then the processed Ti powders were consolidated into the extruded Ti-O-H materials. The additive ULEs' contribution to the microstructures and strengthening behaviour of Ti wrought materials was investigated in detail. The extruded Ti-0.97O-0.11H specimen exhibited an excellent combination of ultimate tensile strength (UTS) of 1158 MPa and tensile elongation of 23.9%, which were superior to those of Ti-6Al-4V alloy (UTS: 1047 MPa, elongation: 16.6%).

Evaluation of near-threshold fatigue crack propagation in harmonic-structured CP titanium with a bimodal grain size distribution

“…The homogeneous fine-grained structure resulting from severe plastic deformation typically decreases the ductility of a metal [11,[14][15][16][17][18], including that of CP titanium [11,14,15], via the early induction of plastic instability. Previous investigations have demonstrated that a new microstructural design can improve both the strength and ductility (or toughness) of some metallic materials [8,[14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31]. As an example, Sergueeva et al [8] reported that both the strength and elongation of CP titanium were improved by high-pressure torsion followed by brief low temperature annealing.…”

Evaluation of the Fatigue Properties of Ti-6Al-4V Alloy with Harmonic Structure in 4-Points Bending

“…Wang et al 4) reported that pure copper with a bimodal grain size distribution created by a thermo-mechanical treatment exhibited stable tensile deformation leading to a high tensile ductility. Kondo et al 7), 8) reported that pure titanium with high strength and high elongation was fabricated by the elemental mixtures of TiH2 and TiO2 powders in solid state. The author's group 9)-15) has developed an exquisite microstructural design, called "harmonic structure", which consists of the coarse-grained structure surrounded by the network structure with fine grains.…”

Recent Advances in the Design and Fabrication of Strong and Ductile (Tensile) Titanium Metal Matrix Composites

“…Surprisingly, recent developments have suggested that these interstitial elements can be used to significantly improve the tensile properties of PM Ti alloys. Figure 7 shows the excellent tensile properties of Ti containing light elements up to 1.66 wt% O, 0.90 wt% N, and 0.33 wt% H. [97][98][99]101,[104][105][106][107]118] For example, Ti-1.66 wt% O alloy achieved UTS ¼ 1378 MPa, YS ¼ 1213 MPa, and tensile elongation ¼ 18.1% [104] ; Ti-0.479 wt% N alloy exhibited UTS ¼ 1146 MPa, YS ¼ 1045 MPa, and tensile elongation ¼ 11%, [101,107] and Ti-0.33 wt% H delivered UTS %960 MPa, YS %800 MPa, and tensile elongation ¼ 27.5%. [99] Hybrid reinforcement by N þ H, O þ N, or O þ H also showed encouraging results.…”

“…[99] Hybrid reinforcement by N þ H, O þ N, or O þ H also showed encouraging results. [105,106,115] For instance, Ti-0.97 wt% O-0.11 wt% H, and Ti-0.6 wt% N-0.07 wt% H showed UTS ¼ 1158 MPa, YS ¼ 990 MPa, elongation ¼ 23.9%, [105] and UTS ¼ 1047 MPa, YS ¼ 918 MPa, elongation ¼ 16.6%, [106] respectively. All these property combinations are superior to these of mill-annealed Ti-6Al-4V.…”