Enhanced tensile strength and high ductility in cryomilled commercially pure titanium

Ertörer, Osman; Topping, Troy D.; Liu, Ying; Moss, Wes; Lavernia, Enrique J.

doi:10.1016/j.scriptamat.2008.12.017

Cited by 76 publications

(34 citation statements)

References 26 publications

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“…The microstructure and mechanical behavior of cryomilled CP-Ti was studied previously by Ertorer et al [13,14] In these studies, balanced combinations of strength and ductility were reported. Also in these studies, quasi-isostatic (QI) forging was used as a consolidation and secondary deformation method.…”

Section: Introductionmentioning

confidence: 93%

“…A similar approach was previously used for cryomilled materials, including Al, [15] Ni, [39] and Ti [13] alloys. A bimodal or multimodal structure can also be formed via thermomechanical treatments and again provide a high ductility.…”

Section: Mechanical Behaviormentioning

confidence: 99%

“…[7][8][9][10][11] This trend is illustrated by reports of CP-Ti with combinations of high tensile strength and good ductility (900-1500 MPa ultimate tensile strength [UTS] and 6-25 pct elongation to failure) as reported in different studies when processed via high-pressure torsion, [9] equal-channel angular pressing (ECAP), [7,12] and cryomilling. [13,14] For example, Semenova et al [7] reported up to 1150 MPa room temperature tensile yield strength (YS) and 1240 MPa UTS with a tensile elongation value of 11 pct, using ECAP followed by a heat treatment step.…”

Section: Introductionmentioning

confidence: 99%

“…The current results are also compared to previous data obtained from cryomilled and QI-forged samples of CP-Ti. [13,32] II. EXPERIMENTAL CP-Ti (grade II) powders (Advanced Specialty Metals, Inc., Nashua, NH) with an average particle size of 55 lm, grain size typically in the 1-30 lm interval, and a chemical composition (in wt pct) of 0.19 pct O, 0.0017 pct N, 0.003 pct C, and 0.013 pct Fe were used as starting materials for the cryomilling experiments.…”

Section: Introductionmentioning

confidence: 99%

“…The selection of a 70 pct cryomilled + 30 pct as-received mixture was motivated by numerous reports on improved ductility in bimodal and multimodal metals, [15,[34][35][36][37][38] as well as earlier experiments on QI-forged cryomilled Ni and Ti. [13,14,39,40] The blended powders were degassed in a closed stainless steel can under vacuum (~10 À3 Pa) at 623 K (350°C) to eliminate moisture and other volatile species using a Varian Turbo-V 70D (Varian Inc., Santa Clara, CA) turbo molecular pump equipped with a Terranova Model 934 vacuum gage controller (Duniway Inc., Mountain View, CA) and a tube furnace. The degassed can was opened and powders were stored in an argon glove box until SPS processing to minimize possible atmospheric contamination.…”

Section: Introductionmentioning

confidence: 99%

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Nanostructured Ti Consolidated via Spark Plasma Sintering

Ertörer

Topping

et al. 2010

Metall Mater Trans A

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Cryomilled nanocrystalline commercially pure (CP)-Ti powders were spark plasma sintered (SPS) using different process parameters (heating rate, temperature, pressure, and dwell time) to study densification, microstructure, and mechanical behavior. The results were rationalized on the basis of the relevant literature and experimental results, and they reveal a strong dependence on SPS parameters. An interesting finding was that the measured high ductility was accompanied by a moderate strength (yield strength [YS] = 770 MPa, ultimate tensile strength [UTS] = 840 MPa with~27 pct elongation to failure). The combinations of microstructure and mechanical response were attributed to the multistep processing at different temperature ranges as well as to the presence of interstitial solutes.

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Section: Introductionmentioning

confidence: 93%

Section: Mechanical Behaviormentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Nanostructured Ti Consolidated via Spark Plasma Sintering

Ertörer

Topping

et al. 2010

Metall Mater Trans A

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Strategies for Improving Tensile Ductility of Bulk Nanostructured Materials

2010

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Strength and ductility are two of the most important mechanical properties of structural materials. High strength is desired for structural components so that they can carry high loads. Good ductility is essential to avoid catastrophic failure in load-bearing applications and is also very important for many shaping and forming operations. The ductility of materials is defined as the extent to which a material can be plastically deformed. Usually, ductility is measured as the elongation to failure in uniaxial tension. It has been a long-standing goal for materials scientists to synthesize structural materials with balanced combinations of high strength and high ductility. However, strength and ductility usually exhibit an inverse relationship; i.e., increasing the strength sacrifices the ductility, and vice versa. This longstanding, strength-ductility empiric conundrum has been partially addressed, for example, by the development of solid solute and dispersion (2nd-phase particles) hardened alloys which have widespread engineering applications but have a lower ductility in comparison with their pure metallic matrix.Since 1980s, bulk nanostructured (NS) materials have emerged as a new class of materials with unusual physical and mechanical behavior and as a result, have attracted considerable attention in recent years. [1] The terminology ''nanostructured'' is generally defined as structural features smaller than 100 nm. [2] Bulk NS materials are single or multi-phase polycrystals with nanoscale grain/subgrain sizes, which are distinct from low-dimensional NS materials such as nanotubes, -wires, -films, and -clusters. Bulk NS materials are structurally characterized by a large volume fraction of grain boundaries (50% for 5 nm grains, 30% for 10 nm grains), which may significantly alter their physical, mechanical, and chemical properties in comparison with those of conventional coarse-grained (CG) materials. The relatively high strength of bulk NS materials, typically 5-10 times of conventional materials of similar composition, offers COMMUNICATIONThe low ductility that is consistently associated with bulk nanostructured (NS) materials has been identified as perhaps the single most critical issue that must be resolved before this novel class of materials can be used in a wide variety of applications. Not surprisingly, a number of published studies, published mostly after 2000, identify the issue of low ductility and describe strategies to improve ductility. Details of these strategies were discussed in review papers published by Ma in 2005 and 2006, respectively. [15,16] In view of continued efforts and recent results, in this paper we describe progress in attempting to address the low ductility of NS materials, after 2006. We first analyze the fundamental reasons for the observed low ductility of bulk NS materials, and summarize early (prior to 2006) attempts to enhance the ductility of bulk NS materials, which often sacrificed the strength. Then, we review recent progress in developing strategies for improving ...

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