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 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 Ti6Al4V Produced by Surface Mechanical Attrition Treatment

2017 ◽  
Vol 898 ◽  
pp. 41-46
Author(s):  
Quan Tong Yao ◽  
Meng Nan Xing ◽  
Guang Lan Zhang ◽  
Wei Ping Tong
Keyword(s):  
Electron Microscopy ◽  
Thermal Stability ◽  
Pure Titanium ◽  
Surface Mechanical Attrition Treatment ◽  
X Ray ◽  
Transmission Electron ◽  
Mechanical Attrition ◽  
Nanocrystalline Layer ◽  
Thermal Stability Of ◽  
Scanning Electron

A pollution-free nanocrystalline layer was prepared on the surface of Ti6Al4V by surface mechanical attrition treatment (SMAT). The nanocrystalline samples were vacuum annealed at various temperatures and for different periods of time. The microstructure and thermal stability were characterized by X-ray (XRD), scanning electron microscopy (SEM) and, transmission electron microscopy (TEM). The results showed that the nanocrystalline Ti6Al4V presented a satisfactory thermal stability with the annealed temperature below 650°C. The critical growth temperature for nanocrystalline Ti6Al4V is 100°C higher than that for pure titanium.

scholarly journals Study of Structure and Mechanical Properties of Fine-Grained Aluminum Alloys Al-0.6wt.%Mg-Zr-Sc with Ratio Zr:Sc = 1.5 Obtained by Cold Drawing

Materials ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 316 ◽  
Author(s):  
Aleksey Nokhrin ◽  
Iana Shadrina ◽  
Vladimir Chuvil’deev ◽  
Vladimir Kopylov
Keyword(s):  
Thermal Stability ◽  
Cold Deformation ◽  
Annealing Treatment ◽  
Cold Drawing ◽  
Fine Grained ◽  
Prolonged Annealing ◽  
Intermetallic Particles ◽  
Average Grain Size ◽  
Fine Grained Structure ◽  
Thermal Stability Of

The thermal stability of a fine-grained (FG) aluminum wire has been studied in Al-0.6Mg-Zr-Sc alloys with various scandium and zirconium contents. Specimens were obtained by induction casting followed by cold deformation. The FG alloys have been demonstrated to have high thermal stability of the structure and properties due to the annealing pretreatment (320 °C, 2 h, before drawing), which results in deposition of Al3(ScxZr1−x) intermetallic particles. It has been determined that following a prolonged annealing treatment (400 °C, 100 h), the alloys retain a uniform fine-grained structure with an average grain size of 2.4–2.8 μm whereas their microhardness measures 405–440 MPa.

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.

Surface Nanocrystallization of Zircaloy-4 by Surface Mechanical Attrition Treatment

2010 ◽  
Vol 658 ◽  
pp. 452-455 ◽  
Author(s):  
Cong Hui Zhang ◽  
Xiao Ge Duan ◽  
Lian Zhou ◽  
Xin Zhe Lan
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Grain Size ◽  
Surface Hardness ◽  
Surface Mechanical Attrition Treatment ◽  
Dislocation Slip ◽  
Transmission Electron ◽  
Mechanical Attrition ◽  
Average Grain Size ◽  
Mechanical Twins

A nanostructured surface layer was induced on zircaloy-4 by the method of surface mechanical attrition treatment (SMAT). X-ray diffraction and microhardness tester were applied to identify the average grain size and hardness of specimen processed for different duration, transmission electron microscopy and high-resolution transmission electron microscopy were adopted to observe the microstructure of specimen. The results showed that the surface hardness enhanced gradually and then stabilized with the processing duration increasing, while the average grain size declined gradually, to the minimum 20 nm at 15 min, then increased. The formation of nanocrystalline was due to the mechanical twins and dislocation slip.

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