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Journal ArticleDOI

Perspectives on Titanium Science and Technology

01 Feb 2013-Acta Materialia (Pergamon)-Vol. 61, Iss: 3, pp 844-879

Abstract: The basic framework and - conceptual understanding of the metallurgy of Ti alloys is strong and this has enabled the use of titanium and its alloys in safety-critical structures such as those in aircraft and aircraft engines. Nevertheless, a focus on cost-effectiveness and the compression of product development time by effectively integrating design with manufacturing in these applications, as well as those emerging in bioengineering, has driven research in recent decades towards a greater predictive capability through the use of computational materials engineering tools. Therefore this paper focuses on the complexity and variety of fundamental phenomena in this material system with a focus on phase transformations and mechanical behaviour in order to delineate the challenges that lie ahead in achieving these goals.
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Journal ArticleDOI
Shunyu Liu1, Yung C. Shin1Institutions (1)
15 Feb 2019-Materials & Design
Abstract: In this paper, the recent progress on Ti6Al4V fabricated by three mostly developed additive manufacturing (AM) techniques-directed energy deposition (DED), selective laser melting (SLM) and electron beam melting (EBM)-is thoroughly investigated and compared. Fundamental knowledge is provided for the creation of links between processing parameters, resultant microstructures and associated mechanical properties. Room temperature tensile and fatigue properties are also reviewed and compared to traditionally manufactured Ti6Al4V parts. The presence of defects in as-built AM Ti6Al4V components and the influences of these defects on mechanical performances are also critically discussed.

593 citations

Journal ArticleDOI
Abstract: Recent research on the additive manufacturing (AM) of Ti alloys has shown that the mechanical properties of the parts are affected by the characteristic microstructure that originates from the AM process. To understand the effect of the microstructure on the tensile properties, selective laser melted (SLM) Ti–6Al–4V samples built in three different orientations were tensile tested. The investigated samples were near fully dense, in two distinct conditions, as-built and stress relieved. It was found that the build orientation affects the tensile properties, and in particular the ductility of the samples. The mechanical anisotropy of the parts was discussed in relation to the crystallographic texture, phase composition and the predominant fracture mechanisms. Fractography and electron backscatter diffraction (EBSD) results indicate that the predominant fracture mechanism is intergranular fracture present along the grain boundaries and thus provide and explain the typical fracture surface features observed in fracture AM Ti–6Al–4V.

471 citations

Journal ArticleDOI
Junheng Gao1, John Nutter1, Xingguang Liu1, Dikai Guan1  +3 moreInstitutions (2)
14 May 2018-Scientific Reports
TL;DR: In this work, instead of addressing the segregation problems, the segregation was utilized to develop a novel microstructure consisting of a nanometre-grained duplex (α+β) structure and micrometre scale β phase with superior mechanical properties.
Abstract: In β titanium alloys, the β stabilizers segregate easily and considerable effort has been devoted to alleviate/eliminate the segregation. In this work, instead of addressing the segregation problems, the segregation was utilized to develop a novel microstructure consisting of a nanometre-grained duplex (α+β) structure and micrometre scale β phase with superior mechanical properties. An as-cast Ti-9Mo-6W alloy exhibited segregation of Mo and W at the tens of micrometre scale. This was subjected to cold rolling and flash annealing at 820 oC for 2 and 5 mins. The solidification segregation of Mo and W leads to a locally different microstructure after cold rolling (i.e., nanostructured β phase in the regions rich in Mo and W and plate-like martensite and β phase in regions relatively poor in Mo and W), which play a decisive role in the formation of the heterogeneous microstructure. Tensile tests showed that this alloy exhibited a superior combination of high yield strength (692 MPa), high tensile strength (1115 MPa), high work hardening rate and large uniform elongation (33.5%). More importantly, the new technique proposed in this work could be potentially applicable to other alloy systems with segregation problems.

422 citations

Journal ArticleDOI
01 Sep 2014-Acta Materialia
Abstract: This study presents results of selective laser melting (SLM) processing of in situ Ti–TiB composites from optimally milled Ti–TiB 2 powder. Optimized tuning of the SLM manufacturing parameters was applied to obtain almost fully dense (>99.5%) Ti–TiB composites. X-ray diffraction and electron diffraction patterns as well as microstructural investigations indicate a chemical reaction during SLM in which irregular-shape titanium diboride (TiB 2 ) particles react with pure Ti to form needle-shape titanium monoboride (TiB) particles. Transmission electron microscopy investigations reveal that Ti grains are refined significantly due to the existence of B. The microhardness, yield stress and compressive strength of the SLM-produced Ti–TiB composites increase to 402 Hv, 1103 MPa and 1421 MPa, respectively, compared to 261 Hv, 560 MPa and 1136 MPa, respectively, for the SLM-produced commercially pure Ti. These improvements are mainly due to strengthening and hardening effects induced by TiB particles and refinement of Ti grains. Fractography analyses show that a mixture of splitting/shearing and smooth/rough zones covers the fracture surfaces of failed composite samples after compression testing.

340 citations

Journal ArticleDOI
Junwei Qiao1, Haoling Jia2, Peter K. Liaw2Institutions (2)
Abstract: The mechanical properties of ex-situ and in-situ metallic glass matrix composites (MGMCs) have proven to be both scientifically unique and of potentially important for practical applications. However, the underlying deformation mechanisms remain to be studied. In this article, we review the development, fabrication, microstructures, and properties of MGMCs, including the room-temperature, cryogenic-temperature, and high-temperature mechanical properties upon quasi-static and dynamic loadings. In parallel, the deformation mechanisms are experimentally and theoretically explored. Moreover, the fatigue, corrosion, and wear behaviors of MGMCs are discussed. Finally, the potential applications and important unresolved issues are identified and discussed.

328 citations

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Abstract: The field of biomaterials has become a vital area, as these materials can enhance the quality and longevity of human life and the science and technology associated with this field has now led to multi-million dollar business. The paper focuses its attention mainly on titanium-based alloys, even though there exists biomaterials made up of ceramics, polymers and composite materials. The paper discusses the biomechanical compatibility of many metallic materials and it brings out the overall superiority of Ti based alloys, even though it is costlier. As it is well known that a good biomaterial should possess the fundamental properties such as better mechanical and biological compatibility and enhanced wear and corrosion resistance in biological environment, the paper discusses the influence of alloy chemistry, thermomechanical processing and surface condition on these properties. In addition, this paper also discusses in detail the various surface modification techniques to achieve superior biocompatibility, higher wear and corrosion resistance. Overall, an attempt has been made to bring out the current scenario of Ti based materials for biomedical applications.

3,382 citations

01 Jan 2003-

1,249 citations

Journal ArticleDOI
Takashi Saito1, Takashi Saito2, Tadahiko Furuta1, Tadahiko Furuta2  +28 moreInstitutions (2)
18 Apr 2003-Science
TL;DR: A group of alloys that exhibit “super” properties, such as ultralow elastic modulus, ultrahigh strength, super elasticity, and super plasticity, at room temperature and that show Elinvar and Invar behavior are described.
Abstract: We describe a group of alloys that exhibit “super” properties, such as ultralow elastic modulus, ultrahigh strength, super elasticity, and super plasticity, at room temperature and that show Elinvar and Invar behavior. These “super” properties are attributable to a dislocation-free plastic deformation mechanism. In cold-worked alloys, this mechanism forms elastic strain fields of hierarchical structure that range in size from the nanometer scale to several tens of micrometers. The resultant elastic strain energy leads to a number of enhanced material properties.

709 citations

Journal ArticleDOI
Isaac Weiss1, S. L. Semiatin2Institutions (2)
Abstract: Thermomechanical processing (TMP) is associated with two major requirements: (i) to produce usable shapes through primary working (ingot breakdown) and secondary mill operations (hot rolling or forging) and (ii) to optimize mechanical properties through microstructure control during the different stages of the thermomechanical process. This paper reviews the thermomechanical processing of beta titanium alloys in general and high temperature deformation mechanisms, microstructure control during TMP, and final mechanical properties in particular.

620 citations

Journal ArticleDOI
Hans Conrad1Institutions (1)

564 citations