Microstructure Evolution of Near Gamma TiAl Intermetallic under Tensile Impact Loadings at High Temperatures

2010 ◽  
Vol 146-147 ◽  
pp. 1553-1556
Author(s):  
Yu Wang ◽  
Xiang Zan ◽  
Yue Hui He ◽  
Yang Wang
Keyword(s):  
Strain Rate ◽  
Microstructure Evolution ◽  
Deformation Mode ◽  
Deformation Twinning ◽  
Stacking Fault ◽  
Effect Of Temperature ◽  
Dislocation Slip ◽  
Tem Analysis ◽  
Dynamic Loadings ◽  
Deformation Modes

The effect of temperature and strain rate on the mechanical behavior and microstructure evolution of Near Gamma Ti-46.5Al-2Nb-2Cr (NG TiAl) was investigated at temperatures ranging from room temperatures to 840 under strain rates of 0.001, 320, 800 and 1350s-1. The TEM analysis indicated that deformation twinning and stacking fault are the main deformation modes under dynamic loadings and dislocation slip is another important deformation mode under quasi-static loadings. The density of deformation twinning and/or stacking fault increases with the increased temperature and strain rate.

On the Formability and Microstructural Characteristics of AISI 301 Parts Formed by Single-Point Incremental Forming

2011 ◽  
Vol 473 ◽  
pp. 869-874 ◽  
Author(s):  
Ivan Lonardelli ◽  
Paolo Bosetti ◽  
Stefania Bruschi ◽  
Alberto Molinari
Keyword(s):  
Incremental Forming ◽  
Early Stage ◽  
Single Point ◽  
Deformation Mode ◽  
Xrd Analysis ◽  
Deformation Twinning ◽  
Dislocation Slip ◽  
Material Object ◽  
Single Point Incremental Forming ◽  
Tem Analysis

The present work focuses on the correlation between the material tendency to be deformed by incremental sheet forming and the microstructural features that appear during the process itself. The material object of the study is the stainless steel AISI 301L. Single-point incremental forming (SPIF) experiments were carried out and the material formability evaluated. X ray diffraction (XRD) analysis was utilized to determine the fraction of transformed martensite along the wall of formed parts at different levels of thickness reduction. TEM analysis was then employed to analyze the microstructure developed during the SPIF process. Two fundamental deformation mechanisms are observed, which could explain the remarkable material formability achievable during the SPIF process: strain induced martensitic transformation, and deformation twinning. Particularly, deformation twinning (instead of dislocation slip) appears to be the preferred plastic deformation mode of austenite at the early stage of the process, leading to the formation of multiple nano-twins in coarse grains that are responsible for the material ductility enhancement.

Microstructure Evolution of TiAl under Tensile Impact Loadings

2013 ◽  
Vol 747-748 ◽  
pp. 14-18
Author(s):  
Xiang Zan ◽  
Li Ouyang ◽  
Yu Wang ◽  
Yue Hui He ◽  
Yong Liu ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Strain Rate ◽  
Microstructure Evolution ◽  
Deformation Process ◽  
High Strain ◽  
Deformation Mode ◽  
Dislocation Slip ◽  
Strain Rates ◽  
Tensile Impact ◽  
Tial Intermetallics

The microstructure evolution of TiAl intermetallics with different microstructures loaded under different strain rates and temperatures was investigated. The results showed that the deformation twinning dominated the deformation process under high strain rate, while dislocation slip was another dominating deformation mode under quasi-static loadings. The proportion of twinned grain increased with the increased strain rate. In Duplex TiAl, the plastic deformation was mainly found in equaxied grains and seldom found in lamellar grains.

Polarization of plastic deformation modes in polysynthetically twinned TiAl crystals

2003 ◽  
Vol 18 (3) ◽  
pp. 702-708 ◽  
Author(s):  
V. Paidar ◽  
K. Kishida ◽  
M. Yamaguchi
Keyword(s):  
Plastic Deformation ◽  
Deformation Mode ◽  
Deformation Twinning ◽  
Additional Stress ◽  
Burgers Vector ◽  
Stress Increase ◽  
Loading Direction ◽  
Deformation Modes ◽  
Lamellar Interfaces

Polarization of deformation twinning (its propagation in a certain sense but not in the opposite one) is taken for granted. However, the same phenomenon can occur for a superdislocation glide as well, as is demonstrated in this paper. The consequences for plastic deformation of polysynthetically twinned TiAl crystals with the lamellar interfaces parallel to the loading direction are discussed. It is not the interface itself that is an obstacle for propagating deformation but also the fact that a deformation mode with the parallel Burgers vector cannot be activated in the neighboring lamella due to the directionality of superdislocation motion leading to additional stress increase.

Strain Path Change Effect on Deformation Behaviour of Materials with Low-to-Moderate Stacking Fault Energy

2008 ◽  
Vol 587-588 ◽  
pp. 420-424 ◽  
Author(s):  
Nataliya A. Sakharova ◽  
Milena M. Vieira ◽  
José Valdemar Fernandes ◽  
Manuel F. Vieira
Keyword(s):  
Shear Modulus ◽  
Microstructure Evolution ◽  
Deformation Behaviour ◽  
True Strain ◽  
Stacking Fault ◽  
Metals And Alloys ◽  
Stacking Fault Energy ◽  
Dislocation Slip ◽  
Strain Paths ◽  
Complex Strain

Stacking fault energy (SFE) plays an important role in face centred cubic (f.c.c.) metals and alloys in determining the prevailing mechanisms of plastic deformation. Low SFE metals and alloys have a tendency to develop mechanical twinning, besides dislocation slip, during plastic deformations. Deformation behaviour and microstructure evolution under simple and complex strain paths were studied in 70/30 brass, with small and intermediate grain sizes, which corresponds to a f.c.c. material with low SFE. Simple (rolling and tension) and complex (tension normal to previous rolling) strain paths were performed. The macroscopic deformation behaviour of materials studied is discussed in terms of equivalent true stress vs. equivalent true strain responses and strain hardening rates normalized by shear modulus (dσ/dε)/G as vs. (σ – σ0)/G (σ0 is the initial yield stress of the material and G is the shear modulus). The mechanical behaviour is discussed with respect to dislocation and twin microstructure evolution developed in both, simple and complex strain paths.

Deformation Twinning, Slip, Martensite Formation and Crack Inhibition in the B2-Type Zr50Pd35Ru15 Alloy

1991 ◽  
Vol 246 ◽  
Author(s):  
R.M. Waterstrat ◽  
L.A. Bendersky ◽  
R. Kuentzler
Keyword(s):  
Crystal Structure ◽  
Plastic Deformation ◽  
Room Temperature ◽  
Deformation Mode ◽  
Deformation Twinning ◽  
Mechanical Twinning ◽  
Dislocation Slip ◽  
Slip Mode ◽  
Martensite Formation ◽  
Additional Mode

AbstractEnhanced room temperature toughness of the Zr50Pd35Ru15B2 phase alloy was found to be a result of the activation of an additional deformation mode besides the b=[001] dislocation slip mode - {114}-type mechanical twinning. The twinning is a true one, i.e. there is no change in the ordered crystal structure. Another additional mode of plastic deformation, expected for more Pd rich alloys, is the formation of stress-induced martensite. The martensite was found to have a CrBtype structure.

TEM Analyses of Microstructure Evolution in Ex-Service Single Crystal CMSX-4 Gas Turbine Blade

2012 ◽  
Vol 186 ◽  
pp. 139-142 ◽  
Author(s):  
Beata Dubiel ◽  
Aleksandra Czyrska-Filemonowicz
Keyword(s):  
Single Crystal ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Microstructure Evolution ◽  
Dislocation Substructure ◽  
Dislocation Climb ◽  
Dislocation Slip ◽  
Gas Turbine Blade ◽  
Tem Analysis ◽  
Blade Height

TEM studies of the ex-service single crystal blade were performed to analyse the microstructural changes which control the degradation of the CMSX-4 superalloy during its exposure in a gas turbine. Microstructural analyses were focused mainly on evolution of the γ-γ’ morphology and examination of dislocation configurations in particular parts of the blade. Between the bottom and tip locations of the blade a pronounced differences in γ-γ’ morphology were observed. TEM analysis of the dislocation substructure showed that at the bottom of the blade the dislocation slip is mainly confined to the horizontal γ channels. Increasing of the temperature and decreasing of stress along the blade height resulted in the γ-γ’ rafting, formation of dislocation networks and intensification of the dislocation climb in vertical γ channels.

Microstructure and Creep Behavior of a Single Crystal Nickel-Base Superalloy with [011] Orientation

2010 ◽  
Vol 654-656 ◽  
pp. 512-515
Author(s):  
Su Gui Tian ◽  
Shu Zhang ◽  
Li Li Yu ◽  
Hui Chen Yu ◽  
Ben Jiang Qian
Keyword(s):  
Strain Rate ◽  
Single Crystal ◽  
Applied Stress ◽  
Deformation Mode ◽  
Dislocation Slip ◽  
Nickel Base Superalloy ◽  
Cubic Phase ◽  
The Matrix ◽  
Nickel Base ◽  
Base Superalloy

An investigation has been made into the microstructure and creep behaviors of [110] oriented single crystal nickel-base superalloy. Results show that, after a full heat treated, the cubic  phase is coherently embedded in the matrix and regularly arranged along the <100> orientation. During creep, the cubic phase in the alloy is transformed into the rafted structure lying 45 relative to the direction of the applied stress. Under the condition of the applied stress of 137 MPa at 1040°C, the alloy displays a higher strain rate and shorter creep lifetime. The deformation mode of the alloy during creep is dislocations activated within the matrix channels and the rafted phase. Dislocation slip activated easily on the Roof-type channel is thought to be the main reason of the alloy having higher strain rate and shorter creep lifetime.

Deformation of Polysynthetically Twinned (PST) TiAl Crystals at High Strain Rate and High Temperature

1996 ◽  
Vol 460 ◽  
Author(s):  
Zhe Jin ◽  
George T. Gray ◽  
Masaharu Yamaguchi
Keyword(s):  
High Temperature ◽  
High Strain ◽  
Deformation Mode ◽  
Dislocation Slip ◽  
Ordinary Dislocation ◽  
Mode 2 ◽  
Lamellar Interface ◽  
Deformation Modes ◽  
Loading Axis ◽  
Lamellar Interfaces

ABSTRACTDeformation microstructures in a 45°<321> oriented (the lamellar interface was tilted 45° from the loading axis about the <321> direction in the lamellar interface) poly synthetically twinned (PST) TiAl crystal deformed in compression at 3000 s-1 and 800 °C was studied. Deformation of this PST crystal is characterized as follows: 1) Deformation of domains [III] and [IV] is dominated by 1/6 [112] parallel twinning (twinning parallel to lamellar interfaces). Ordinary dislocations observed in these domains are found to be a complementary deformation mode. 2) Deformation of domains [II], [V] and [VI] is controlled by a 1/2<110] ordinary dislocation slip. Complementary deformation modes in these domains are ordinary dislocation slip, superdislocation slip and cross-twinning. 3) Domain [I] is not deformed after the specimen deforms up to ∼7% strain.

Mechanoactivation of Spiropyran Covalently Linked PMMA: Effect of Temperature, Strain Rate, and Deformation Mode

2015 ◽  
Vol 48 (5) ◽  
pp. 1335-1342 ◽  
Author(s):  
Jae Woo Kim ◽  
Yukyung Jung ◽  
Geoffrey W. Coates ◽  
Meredith N. Silberstein
Keyword(s):  
Strain Rate ◽  
Deformation Mode ◽  
Effect Of Temperature ◽  
Covalently Linked ◽  
Temperature Strain
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