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

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 10nm after 90min 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∘C. BCC-Ti nanocrystallites were shown to exhibit excellent thermal stability up to 650∘C, whereas those in HCP-Ti started to recrystallize at approximately 550∘C.

[1]  Jian Sun,et al.  Enhanced toughness of nitrided layers formed on Ti-6Al-4V alloy via surface mechanical attrition pre-treatment , 2017 .

[2]  Chuan Xu,et al.  Effect of high energy shot peening on the microstructure and mechanical properties of Mg/Ti joints , 2017 .

[3]  B. Miao,et al.  The effect of sand blasting pretreatment on plasma nitriding , 2017 .

[4]  Jian Sun,et al.  An Evaluation of a Borided Layer Formed on Ti-6Al-4V Alloy by Means of SMAT and Low-Temperature Boriding , 2016, Materials.

[5]  Huijun Li,et al.  Microstructural evolution, mechanical property and thermal stability of Al–Li 2198-T8 alloy processed by high pressure torsion , 2016 .

[6]  N. Haghdadi,et al.  Thermal stability of an ultrafine-grained dual phase TWIP steel , 2015 .

[7]  Jian Lu,et al.  Mechanical properties and thermal stability of nanocrystallized pure aluminum produced by surface mechanical attrition treatment , 2015 .

[8]  T. Langdon,et al.  Effect of temperature on microstructural stabilization and mechanical properties in the dynamic testing of nanocrystalline pure Ti , 2015 .

[9]  H. Nykyforchyn,et al.  Effect of Nanostructurisation of Structural Steels on its Wear Resistance and Hydrogen Embittlement Resistance , 2014 .

[10]  Zhi-Gang Yang,et al.  Microstructure and thermal stability of bulk nanocrystalline alloys produced by surface mechanical attrition treatment , 2014 .

[11]  C. Richard,et al.  Effect of surface nanocrystallization on the corrosion behavior of Ti–6Al–4V titanium alloy , 2013 .

[12]  Jian Sun,et al.  Low-temperature plasma nitriding of titanium layer on Ti/Al clad sheet , 2013 .

[13]  Yong Han,et al.  Structure evolution and thermal stability of SMAT-derived nanograined layer on Ti–25Nb–3Mo–3Zr–2Sn alloy at elevated temperatures , 2013 .

[14]  H. Benhayoune,et al.  Surface nanocrystallization of Ti-6Al-4V alloy: microstructural and mechanical characterization. , 2012, Journal of nanoscience and nanotechnology.

[15]  Yong Yang,et al.  Thermal stability of ultrafine grained Fe–Cr–Ni alloy , 2012 .

[16]  Lin Xiao,et al.  Thermal stability of bulk nanocrystalline Ti–10V–2Fe–3Al alloy , 2012 .

[17]  Liang Wang,et al.  The effect of surface nanocrystallization on plasma nitriding behaviour of AISI 4140 steel , 2010 .

[18]  Guobin Li,et al.  Friction and wear behaviors of nanocrystalline surface layer of medium carbon steel , 2010 .

[19]  A. L. Ortiz,et al.  Experimental study of the microstructure and stress state of shot peened and surface mechanical attrition treated nickel alloys , 2010 .

[20]  N. Yu,et al.  Thermal stability of nanocrystalline layers fabricated by surface nanocrystallization , 2010 .

[21]  K. Lu,et al.  Structural refinement and deformation mechanisms in nanostructured metals , 2009 .

[22]  Chong-xiang Huang,et al.  Tensile and compressive properties of AISI 304L stainless steel subjected to equal channel angular pressing , 2008 .

[23]  Juncai Sun,et al.  The effects of severe surface deformation on plasma nitriding of austenitic stainless steel , 2005 .

[24]  S. Tjong,et al.  Nanocrystalline materials and coatings , 2004 .

[25]  Jian Lu,et al.  Nanostructure formation mechanism of α-titanium using SMAT , 2004 .

[26]  R. Valiev,et al.  Nanostructuring of metals by severe plastic deformation for advanced properties , 2004, Nature materials.

[27]  F. Banhart,et al.  Formation of face-centered-cubic titanium by mechanical attrition , 2003 .

[28]  Jian Lu,et al.  An investigation of surface nanocrystallization mechanism in Fe induced by surface mechanical attrition treatment , 2002 .

[29]  W. Kim,et al.  Mechanical properties and microstructures of an AZ61 Mg Alloy produced by equal channel angular pressing , 2002 .

[30]  Lu,et al.  Superplastic extensibility of nanocrystalline copper at room temperature , 2000, Science.

[31]  Zushu Hu,et al.  Evolution of dislocation structure induced by cyclic deformation in a directionally solidified cobalt base superalloy , 1999 .

[32]  Jan Sieniawski,et al.  The effect of microstructure on the mechanical properties of two-phase titanium alloys , 1997 .

[33]  C. Koch,et al.  Formation of amorphous alloys by the mechanical alloying of crystalline powders of pure metals and powders of intermetallics , 1986 .