Study on the Structure and Properties of Surface Nanocrystallized Zr-4

2011 ◽  
Vol 415-417 ◽  
pp. 660-665
Author(s):  
Cong Hui Zhang ◽  
Da Li Liu ◽  
Xin Zhe Lan ◽  
Xi Cheng Zhao
Keyword(s):  
Surface Roughness ◽  
Surface Layer ◽  
Processing Time ◽  
Optical Microscope ◽  
Surface Mechanical Attrition Treatment ◽  
Structure And Properties ◽  
Nanostructured Surface ◽  
Grain Sizes ◽  
Mechanical Attrition ◽  
Average Grain Size

A nanostructured surface layer was obtained on the surface of Zr-4 by surface mechanical attrition treatment(SMAT). The structure and the properties of the SMAT sample were analyzed by means of the optical microscope, hardness and polarization curve testing. The results show that， when processing time for 5min, the average grain sizes on the surface layer can be refined to 23nm. The average grain size by SMAT-ed for 15min is 20nm, which is the smallest. The microhardness have a significant increase, the surface roughness also increase, and the corrosion resistance reduce in 1mol H2SO4solution.

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.

scholarly journals MICROSTRUCTURE EVOLUTION AND DEFORMATION FEATURE OF AZ31 MAGNESIUM ALLOY DURING SEVERE PLASTIC DEFORMATION

2012 ◽  
Vol 06 ◽  
pp. 503-508
Author(s):  
LI-FENG HOU ◽  
YING-HUI WEI ◽  
XUE-FENG SHU
Keyword(s):  
Surface Layer ◽  
Magnesium Alloy ◽  
Microstructure Evolution ◽  
Az31 Magnesium Alloy ◽  
Surface Mechanical Attrition Treatment ◽  
Nanostructured Surface ◽  
Deformation Feature ◽  
Transmission Electron ◽  
Mechanical Attrition ◽  
Refinement Process

A nanostructured surface layer was produced on commercially AZ31 magnesium alloy using surface mechanical attrition treatment (SMAT). The microstructure evolution and deformation feature along the depth of the treated surface layer were characterized by transmission electron microscope (TEM) investigations. The grain refinement process, accompanied by an increase in the surface layer, involves: the onset of twins; the formation of microbands associated with the dislocation slipping; the subdivision of microbands into low angle grains and then highly disoriented polygonal submicronic grains, and further breakdown into randomly oriented nanograins with progression of dynamic recrystallization.

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.

Tribological Behaviors of Nanostructured Surface Layer Processed by Means of Surface Mechanical Attrition Treatment

2008 ◽  
Vol 384 ◽  
pp. 321-334 ◽  
Author(s):  
Yi Nong Shi ◽  
Zhong Han
Keyword(s):  
Surface Layer ◽  
Sliding Wear ◽  
Friction And Wear ◽  
Wear Behavior ◽  
Surface Mechanical Attrition Treatment ◽  
Nanostructured Surface ◽  
Chemical Treatments ◽  
Mechanical Attrition ◽  
Potential Applications ◽  
Refinement Mechanism

Surface mechanical attrition treatment, an approach to fabricate nanostructured surface layer on bulk metallic materials has been extensively investigated in the past few years with respect to grain refinement mechanism, friction and wear behavior and the subsequent chemical treatments. The present paper briefly overviews the friction and wear behaviors of the surface nanocrystalline layers generated by SMAT on Cu, steels and Mg alloy with emphasis on reciprocating sliding wear behaviors. The potential applications of the present approach are also prospected.

scholarly journals Investigation of Surface Self-Nanocrystallization in 0Cr18Ni9Ti Induced by Surface Mechanical Attrition Treatment

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
Guangmin Sheng
Keyword(s):  
Surface Layer ◽  
Surface Mechanical Attrition Treatment ◽  
Cross Sectional ◽  
Characterization Methods ◽  
Microhardness Distribution ◽  
Mechanical Attrition ◽  
Nanostructured Layer ◽  
Average Grain Size ◽  
Sectional Surface ◽  
Xrd Patterns

By means of shot peening (a form of surface mechanical attrition treatment (SMAT)), a nanostructured surface layer was formed on the cross-sectional surface of a 0Cr18Ni9Ti bar. Several characterization methods in common use, such as OM, SEM, TEM, and XRD, were adopted to systematically characterize microstructure features of the nanostructured layer in the top surface of the sample. Microstructure features of the surface layer, which appeared mainly as severely deformed and contained grains with size in nanomagnitude, could be intuitionisticly presented through OM, SEM, and TEM. XRD was a useful method and average grain size and mean microstrain could be quantitatively calculated from the XRD patterns. In addition, analyses of XRD patterns showed that there was a martensite transformation in the top surface layer. Microhardness distribution along the depth of the deformation layer from the top surface showed that the surface self-nanocrystallization (SSNC) layer is a gradient structure and that the hardness of the top surface is greatly enhanced due to grain refinement and work hardening.

Thermal Stability of Nanocrystalline BCC-Ti Formed by Phase Transformation During Surface Mechanical Attrition Treatment

NANO ◽  
2017 ◽  
Vol 12 (09) ◽  
pp. 1750113 ◽  
Author(s):  
Quantong Yao ◽  
Jian Sun ◽  
Guanglan Zhang ◽  
Weiping Tong ◽  
Hui Zhang
Keyword(s):  
Electron Microscopy ◽  
Thermal Stability ◽  
Phase Transformation ◽  
Surface Layer ◽  
Annealing Treatment ◽  
Surface Mechanical Attrition Treatment ◽  
Excellent Thermal Stability ◽  
Mechanical Attrition ◽  
Average Grain Size ◽  
Thermal Stability Of

This paper reports the transformation of HCP-Ti into BCC-Ti in the Ti–6Al–4V alloy induced by surface mechanical attrition treatment (SMAT). The processes of surface nanocrystallization (SNC) and phase transformation were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that the average grain size in the surface layer gradually decreased with increasing SMAT duration, but plateaued at 10[Formula: see text]nm after 90[Formula: see text]min of SMAT, while the proportion of BCC-Ti in the surface layer gradually increased. The refined grains displayed equiaxed grain morphology with a random crystallographic orientation. The thermal stability of nanocrystalline BCC-Ti was investigated by subjecting it to isothermal annealing treatment in the temperature range of 450–800[Formula: see text]C. BCC-Ti nanocrystallites were shown to exhibit excellent thermal stability up to 650[Formula: see text]C, whereas those in HCP-Ti started to recrystallize at approximately 550[Formula: see text]C.

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