Thermal stability and corrosion resistance of nanocrystallized zirconium formed by surface mechanical attrition treatment

2009 ◽  
Vol 24 (10) ◽  
pp. 3136-3145 ◽  
Author(s):  
Yong Han ◽  
Lan Zhang ◽  
Jian Lu ◽  
Wengting Zhang
Keyword(s):  
Thermal Stability ◽  
Grain Size ◽  
Corrosion Resistance ◽  
Grain Growth ◽  
Coarse Grained ◽  
Surface Mechanical Attrition Treatment ◽  
Passive Protection ◽  
Mechanical Attrition ◽  
Nanostructured Layer ◽  
Pure Zirconium

The thermal stability and corrosion behavior of the nanostructured layer on commercially pure zirconium, produced by surface mechanical attrition treatment (SMAT), were investigated. It is indicated that the nanograined Zr is stable at annealing temperatures up to 650 °C, above which significant grain growth occurs and the grain size shows parabolic relationship with annealing time. The activation energy for grain growth of the nanograined Zr is 59 kJ/mol at 750–850 °C, and the grain growth is dominated by grain-boundary diffusion. The as-SMATed nanograined Zr exhibits higher corrosion resistance than the 550–750 °C annealed SMATed Zr and the unSMATed coarse-grained Zr. It is indicated that the corrosion resistance of Zr tends to increase with the reduction of grain size, which is related to the dilution of segregated impurities at grain boundaries due to grain refinement and the formation of passive protection film.

Thermal Stability of Nanocrystallized Surface Layer in Al-Zn-Mg Alloy by Surface Mechanical Attrition Treatment

2007 ◽  
Vol 546-549 ◽  
pp. 1129-1134 ◽  
Author(s):  
Jin Fang Ma ◽  
Lan Qing Hu ◽  
Xu Guang Liu ◽  
Bing She Xu
Keyword(s):  
Thermal Stability ◽  
Grain Size ◽  
Surface Layer ◽  
Boundary Migration ◽  
Mg Alloy ◽  
Surface Mechanical Attrition Treatment ◽  
Mechanical Attrition ◽  
Nanostructured Layer ◽  
Average Grain Size ◽  
Thermal Stability Of

After surface mechanical attrition treatment (SMAT) for Al-Zn-Mg alloy, a gradient structure with average grain size increased from 20nm in surface layer to about 100nm at a depth of 20μm was formed. The thermal stability of surface nanostructured layer in Al-Zn-Mg alloy samples was investigated by vacuum annealing at 100°C, 150°C, 200°C and 250°C for 1h, respectively. The microstructural evolution as well as the microhardness along the depth from top surface layer to matrix of SMATed samples was analyzed. Experimental results showed that the grain size of surface nanocrystallites remains in submicro-scale, ranging from 300nm to 400nm, when annealed at a temperature of 250°C, and the microhardness of surface nanostructured layer was still high compared with that of matrix, indicating satisfying thermal stability of nanocrystallized layer. This might be attributed to the presence of substantive trident grain boundaries and pinning effect of dispersive precipitated phases in nanocrystalline materials, which hindered the grain boundary migration that leading to grain growth.

Wear Behaviour of Pure Ti with a Nanocrystalline Surface Layer

2011 ◽  
Vol 66-68 ◽  
pp. 1500-1504 ◽  
Author(s):  
Ming Wen ◽  
Cui'e Wen ◽  
Peter D. Hodgson ◽  
Yun Cang Li
Keyword(s):  
Grain Size ◽  
Wear Resistance ◽  
Titanium Surface ◽  
Pure Titanium ◽  
Coarse Grained ◽  
Surface Mechanical Attrition Treatment ◽  
Wear Behaviour ◽  
Wear Properties ◽  
Microstructure Observation ◽  
Mechanical Attrition

A nanocrystalline (NC) layer with the thickness of 30 µm was produced on pure titanium surface by surface mechanical attrition treatment (SMAT). Microstructure observation indicated that the grain size increases with depth from the treated surface. The friction coefficient decreases and the wear resistance increases with the SMAT sample as compared to its coarse-grained counterpart. The improvement of the wear properties could be attributed to the higher hardness of SMAT sample.

Interface Diffusion in Cu Processed by Means of Surface Mechanical Attrition Treatment

2009 ◽  
Vol 289-292 ◽  
pp. 557-563 ◽  
Author(s):  
Z.B. Wang ◽  
K. Wang ◽  
K. Lu ◽  
Gerhard Wilde ◽  
Sergiy V. Divinski
Keyword(s):  
Grain Size ◽  
Surface Layer ◽  
Subsurface Layer ◽  
Coarse Grained ◽  
Surface Mechanical Attrition Treatment ◽  
Nanostructured Surface ◽  
Radiotracer Technique ◽  
Mechanical Attrition ◽  
The Difference ◽  
Effective Diffusivities

A nanostructured surface layer with a gradient microstructure was produced on a Cu plate by means of the surface mechanical attrition treatment (SMAT). Diffusion of Ni in the nanostructured layer was investigated by the radiotracer technique at temperatures from 383 to 438 K. The measured diffusion profiles consist of two distinct sections with different slopes, the steep one corresponding to the top surface layer with the grain size of 10 to 25 nm and the shallow one corresponding to a subsurface layer with a grain size of 25 to 100 nm. The effective diffusivities derived from both sections are more than 2 orders of magnitudes higher than the grain boundary diffusivities in coarse-grained Cu. The significantly accelerated diffusion rates are expected to be associated with the “non-equilibrium” states of interfaces in the nanostructured surface layer induced by SMAT. The difference between the diffusivities in the top and sub- surface layer might result from the fact that most interfaces developed from twin boundaries in the former while produced by dislocation activities in the latter.

The Effect of Grain Size on Superplastic Deformation of Ti-6Al-4V Alloy

2007 ◽  
Vol 551-552 ◽  
pp. 387-392 ◽  
Author(s):  
Wen Juan Zhao ◽  
Hua Ding ◽  
D. Song ◽  
F.R. Cao ◽  
Hong Liang Hou
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Superplastic Deformation ◽  
Initial Strain Rate ◽  
Deformation Mode ◽  
Tensile Tests ◽  
Optical Microscope ◽  
Coarse Grained ◽  
Transmission Electron ◽  
Grain Growth Model

In this study, superplastic tensile tests were carried out for Ti-6Al-4V alloy using different initial grain sizes (2.6 μm, 6.5μm and 16.2 μm) at a temperature of 920°C with an initial strain rate of 1×10-3 s-1. To get an insight into the effect of grain size on the superplastic deformation mechanisms, the microstructures of deformed alloy were investigated by using an optical microscope and transmission electron microscope (TEM). The results indicate that there is dramatic difference in the superplastic deformation mode of fine and coarse grained Ti-6Al-4V alloy. Meanwhile, grain growth induced by superplastic deformation has also been clearly observed during deformation process, and the grain growth model including the static and strain induced part during superplastic deformation was utilized to analyze the data of Ti-6Al-4V alloy.

Grain Growth in Nanocrystalline Nickel

1999 ◽  
Vol 580 ◽  
Author(s):  
G.D. Hibbard ◽  
U. Erb ◽  
K.T. Aust ◽  
G. Palumbo
Keyword(s):  
Thermal Stability ◽  
Grain Size ◽  
Grain Growth ◽  
Size Distributions ◽  
Nanocrystalline Nickel ◽  
Scanning Calorimetry ◽  
Solute Content ◽  
Grain Size Distributions ◽  
Thermal Stability Of ◽  
Total Solute Content

AbstractIn this study, the effect of grain size distribution on the thermal stability of electrodeposited nanocrystalline nickel was investigated by pre-annealing material such that a limited amount of abnormal grain growth was introduced. This work was done in an effort to understand the previously reported, unexpected effect, of increasing thermal stability with decreasing grain size seen in some nanocrystalline systems. Pre-annealing produced a range of grain size distributions in materials with relatively unchanged crystallographic texture and total solute content. Subsequent thermal analysis of the pre-annealed samples by differential scanning calorimetry showed that the activation energy of further grain growth was unchanged from the as-deposited nanocrystalline nickel.

Surface Nanocrystallines of Fe3Al Produced by Surface Mechanical Attrition

2011 ◽  
Vol 320 ◽  
pp. 325-328 ◽  
Author(s):  
Jiang Wei Ren ◽  
Dong Li ◽  
Pei Quan Xu
Keyword(s):  
Grain Size ◽  
Surface Layer ◽  
Surface Mechanical Attrition Treatment ◽  
Electronic Microscopy ◽  
X Ray ◽  
Structure And Morphology ◽  
Mechanical Attrition ◽  
Deformed Layer ◽  
Fe3al Intermetallic ◽  
Morphology Of Surface

A nanocrystallines surface layer was produced in Fe3Al intermetallic compound by surface mechanical attrition treatment (SMAT). The microstructure of deformed layer, phase structure and morphology of surface nanocrystallines were characterized through optical microscopy, X-ray diffractometry, transmission electronic microscopy and high resolution electronic microscopy. The results show that a deformed layer about 11μm wide is produced after 10min surface mechanical attrition. The grains on the top surface of Fe3Al are refined to nanocrystallines and the grain size of nanocrystallines is about 35nm. High density dislocations collect on the boundaries of grains. The formation of nanocrystallines is controlled by grain subdivision mechanism.

Influences of Grain Size on Electrochemical Corrosion Behaviors of Nickel-Based Alloy 718

2016 ◽  
Vol 852 ◽  
pp. 105-112 ◽  
Author(s):  
Yan Mo ◽  
Dong Zhe Wang ◽  
Bin Jiang ◽  
Yong You Li ◽  
Hai Ding Liu ◽  
...  
Keyword(s):  
Grain Size ◽  
Corrosion Resistance ◽  
Sea Water ◽  
Electrochemical Impedance ◽  
Electrochemical Corrosion ◽  
Structure Design ◽  
Coarse Grained ◽  
Alloy 718 ◽  
Corrosion Behaviors ◽  
Nickel Based Alloy

With the application upgrade of alloy 718 in the marine oil exploitation, higher corrosion resistance demands has been presented for structure design and reasonable material application of drilling and production equipments; thus there is an urgent need to understand influences of grain size on corrosion behavior of such alloy in sea water environment. In this experiment, different solution treatments are applied to nickel-based alloy 718. As a result, specimens with grain size varied from ASTM No. 9 to No. 3.5 grades. The influences of grain size on the electrochemical behaviors in simulated sea water (3.5% sodium chloride solution) are investigated using electrochemical impedance spectroscopy and polarization curves. Alloy 718 shows good corrosion resistance in this electrolyte solution, however, grain size still has an effect on its electrochemical corrosion behaviors to a certain extent. With the time going, testing results show that coarse-grained alloys with larger grain size have higher impedance values and smaller corrosion current densities, indicating a better corrosion resistance than fine-grained specimens. However, when the grain size increases further, the corrosivity resistant nature of alloy 718 would decline. Testing results show that specimen with size of ASTM No. 5 has the best corrosion resistance.

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