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.

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.

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.

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 40Cr Steel with Surface Nanocrystallization

2006 ◽  
Vol 510-511 ◽  
pp. 434-437 ◽  
Author(s):  
Yu Liang Liu ◽  
Tian Ying Xiong ◽  
Ke Yang
Keyword(s):  
Thermal Stability ◽  
Surface Layer ◽  
Nanostructured Materials ◽  
High Thermal Stability ◽  
New Method ◽  
Nanostructured Surface ◽  
Surface Nanocrystallization ◽  
Nanostructured Layer ◽  
40Cr Steel ◽  
Thermal Stability Of

Surface Nanocrystallization(SNC) is a new method of fabricating nanostructured materials while thermal stability is an important problem for the application of nanostructured materials. A nanostructured layer was fabricated on the surface of 40Cr steel by Supersonic Particles Bombarding method, and the variation of microstructure and microhardness of nanostructured layer was studied. Nanostructured surface layer showed high thermal stability.

Thermal Stability of Ultrafine-Grained Pure Titanium Processed by High-Pressure Torsion

2021 ◽  
Vol 1016 ◽  
pp. 338-344
Author(s):  
Wan Ji Chen ◽  
Jie Xu ◽  
De Tong Liu ◽  
De Bin Shan ◽  
Bin Guo ◽  
...  
Keyword(s):  
Activation Energy ◽  
Thermal Stability ◽  
Grain Size ◽  
High Pressure ◽  
Annealing Temperature ◽  
High Pressure Torsion ◽  
Stored Energy ◽  
Ultrafine Grained ◽  
Average Grain Size ◽  
Thermal Stability Of

High-pressure torsion (HPT) was conducted under 6.0 GPa on commercial purity titanium up to 10 turns. An ultrafine-grained (UFG) pure Ti with an average grain size of ~96 nm was obtained. The thermal properties of these samples were studied by using differential scanning calorimeter (DSC) which allowed the quantitative determination of the evolution of stored energy, the recrystallization temperatures, the activation energy involved in the recrystallization of the material and the evolution of the recrystallized fraction with temperature. The results show that the stored energy increases, beyond which the stored energy seems to level off to a saturated value with increase of HPT up to 5 turns. An average activation energy of about 101 kJ/mol for the recrystallization of 5 turns samples was determined. Also, the thermal stability of the grains of the 5 turns samples with subsequent heat treatments were investigated by microstructural analysis and Vickers microhardness measurements. It is shown that the average grain size remains below 246 nm when the annealing temperature is below 500 °C, and the size of the grains increases significantly for samples at the annealing temperature of 600 °C.

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.

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