Strategies for Improving Ductility of Cryomilled Nanostructured Titanium

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

doi:10.4028/www.scientific.net/msf.633-634.459

Cited by 2 publications

(2 citation statements)

References 34 publications

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“…However, it is very difficult to control abnormal grain growth to produce a desirable bi‐modal grain size distribution by annealing NS samples. Recently, we proposed an improved approach to produce bi‐modal or multi‐modal grain structures using the cryomilling method 6, 38, 39. In this approach, NS metal powders (such as Ni and Ti) processed by cryo‐milling were mixed with CG powders at designated ratios and then quasi‐isostatic Ceracon forged to produce large, fully dense samples.…”

Section: Approaches That Improve High Ductility But Sacrifice Strengthmentioning

confidence: 99%

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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Section: Approaches That Improve High Ductility But Sacrifice Strengthmentioning

confidence: 99%

Strategies for Improving Tensile Ductility of Bulk Nanostructured Materials

2010

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“…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%

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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Strategies for Improving Ductility of Cryomilled Nanostructured Titanium

Cited by 2 publications

References 34 publications

Strategies for Improving Tensile Ductility of Bulk Nanostructured Materials

Strategies for Improving Tensile Ductility of Bulk Nanostructured Materials

Nanostructured Ti Consolidated via Spark Plasma Sintering

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