This paper reports the stability of Ti-5Al-5Mo-5V-3Cr and similar Mo equivalent alloys using first principles calculations. The lattice constant and modulus values are calculated using X-ray diffraction and ultrasonic techniques, respectively. All the four alloys display negative values of formation energy per atom and the alloy Ti-5Al-5Mo-5V-3Cr is most stable among these. The lattice constant, modulus and hardness values of these alloys lie in low (Ti-5Al-5Mo-5V-3Cr, Ti-5Al-5Mo-8.6V-1.5Cr) and high (Ti-5Al-3.5Mo-7.2V-3Cr, Ti-5Al-3.5Mo-5V-3.94Cr) regimes. All the alloys display ductile behavior based on shear and bulk modulus ratios. © 2017 Universidad Nacional Autónoma de México, Centro de Ciencias Aplicadas y Desarrollo Tecnológico

Chakkingal Uday

Department of Metallurgical and Materials Engineering

Fulltext

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Journal of Applied Research and Technology

Present work describes the development of the α phase in β WQ specimens of Ti-5Al-5Mo-5V-3Cr (A1), Ti-5Al-3.5Mo-7.2V-3Cr (A2), Ti-5Al-5Mo-8.6V-1.5Cr (A3) and Ti-5Al-3.5Mo-5V-3.94Cr (A4) alloys as function of different ageing temperatures and time intervals. The α phase formed during ageing display different morphologies namely, thin film on prior β grain boundaries, sub boundary and islands of the α phase within the β matrix. Mechanism of the formation of these morphologies has been explained. The fine and even distribution of the α phase in β matrix exhibit two distinct features i.e. uniform distribution of α laths with two variants and clusters of parallel α laths. The α phase presents in all morphologies is transformed to Widmanstatten type morphology on further increase in ageing temperature and time. The development of the α phase in these alloys at 300 and 400 °C results in significant increase in hardness which is attributed to typical precipitation hardening. © 2016 Elsevier Inc.

Materials Characterization

Development of α precipitates in metastable Ti-5Al-5Mo-5V-3Cr and similar alloys

This paper describes the tensile properties, flow and work-hardening behavior of four metastable β-titanium alloys Ti-5Al-5Mo-5V-3Cr (A1), Ti-5Al-3.5Mo-7.2V-3Cr (A2), Ti-5Al-5Mo-8.6V-1.5Cr (A3), and Ti-5Al-3.5Mo-5V-3.94Cr (A4) in α+β hot-rolled condition. The decreasing order of average strength parameters (σYS and σUTS) is A4, A2, A1, and A3. The maximum strength observed in alloy A4 is due to the presence of highest wt. fraction of Cr. The elongation is the maximum and minimum in alloys A3 and A4, respectively. These alloys display moderate to high percent in-plane anisotropy (AIP) and reasonably low anisotropic index (δ) values. Both the AIP and δ values are maximum and minimum in alloys A1 and A3, respectively. The yield locus plots also exhibit the presence of anisotropy due to relatively large differences in yield strength values along tension and compression directions. The flow behavior of alloys A1, A2, and A4 follows Swift equation, while the alloy A3 displays best fit with Holloman equation. The presence of prestrain (ε0) in hot-rolled materials before tensile testing has an important bearing on the flow curves of A1, A2, and A4 alloys. The instantaneous work-hardening rate curves of the alloys A1, A2, and A3 exhibit all the three typical stages (stage I, stage II, and stage III) in RD samples, while the alloy A4 shows the presence of only stage I and stage III. The 45 deg to RD and TD samples of alloys A1, A2, and A4 display only stage I. The stages I and III as well as I and II are present in alloy A3 in 45 deg to RD and TD samples, respectively. Dislocation-controlled strain hardening occurs in all the three stages of these alloys in the absence of stress-induced martensitic transformation (α″) and twinning. Slip is the predominant deformation mechanism during tensile testing. Three types of slip lines, i.e., planar, wavy, and intersecting have been observed close to fracture surfaces of post tensile-tested specimens. © 2016, The Minerals, Metals & Materials Society and ASM International.

Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science

Effect of Alloying Elements in Hot-Rolled Metastable β-Titanium Alloys. Part II: Mechanical Properties

The present work describes the evolution of microstructures and textures in alloys Ti-5Al-5Mo-5V-3Cr (A1), Ti-5Al-3.5Mo-7.2V-3Cr (A2), Ti-5Al-5Mo-8.6V-1.5Cr (A3), and Ti-5Al-3.5Mo-5V-3.94Cr (A4) during unidirectional hot rolling. The hot-rolled microstructures of the alloy A1 exhibit large fraction of recovered/recrystallized grains, while the alloy A3 shows small fraction of recovered/recrystallized grains. The alloy A2 displays subgrains and recrystallized grains, while the alloy A4 exhibits the microstructure consisting of the features of both the alloys A1 and A2. The alloys A1, A3, and A4 show the presence of shear bands within the β grains and also small volume fraction of the α phase. The dominance of deformation and/or recrystallization components in respective α and γ fibers varies with alloy compositions and hot rolling reductions. In alloys A1 and A2, deformation components dominate from 30 to 50 pct rolling reductions, while recrystallization components govern in 70 pct rolled samples. The deformation components prevail from 30 to 70 pct rolling reductions in alloy A3. The alloy A4 exhibits softening of texture due to recovery or early stage of recrystallization from 30 to 50 pct reductions, while texture present in 70 pct rolled sample consists of mainly the deformation components. The role of molybdenum appears to be quite critical in the evolution of microstructures and textures of these alloys. The alloys with low and high Mo contents display high and low amount of the α phase, respectively. © 2015, The Minerals, Metals & Materials Society and ASM International.

Effect of Alloying Elements in Hot-Rolled Metastable β-Titanium Alloys: Part I. Evolution of Microstructure and Texture

Present work describes the formation of shear bands during Vickers indentation with indentation loads in the range of 0.1 to 20 kg in four metastable β titanium alloys in β water quench condition. Extent of solid solution has marked influence on the evolution of shear bands. All the four alloys exhibit both the primary and secondary shear bands. The spacing between shear bands increases with increase in distance from the indenter edge. Crystal orientation mapping has been used to measure misorientations at different locations within the matrix, shear bands and at the interface between matrix and shear band. © 2014 Elsevier Inc.

Journal	Journal of Applied Research and Technology
Publisher	Universidad Nacional Autonoma de Mexico, Centro de Ciencias Aplicadas y Desarrollo Tecnologico
ISSN	16656423
Open Access	Yes