Residual elastic stress–strain field and geometrically necessary dislocation density distribution around nano-indentation in TA15 titanium alloy

• Published in: Transactions of Nonferrous Metals Society of China 2013-01, Vol.23 (1), p.7-13
• Main Authors: HE, Dong, ZHU, Jing-chuan, LAI, Zhong-hong, LIU, Yong, YANG, Xia-wei, NONG, Zhi-sheng
• Format: Article
• Language: English
• Subjects: Beta; Density; Elastic modulus; electron backscatter diffraction; geometrically necessary dislocation; Indentation; Modulus of elasticity; nano-hardness; nanoindentation; Nanostructure; Phases; Stress concentration; stress–strain fields; TA15 titanium alloy; Titanium base alloys
• ISSN: 1003-6326
• DOI: 10.1016/S1003-6326(13)62422-X

Nanoindentation and high resolution electron backscatter diffraction (EBSD) were combined to examine the elastic modulus and hardness of α and β phases, anisotropy in residual elastic stress–strain fields and distributions of geometrically necessary dislocation (GND) density around the indentations within TA15 titanium alloy. The nano-indention tests were conducted on α and β phases, respectively. The residual stress–strain fields surrounding the indentation were calculated through cross-correlation method from recorded patterns. The GND density distribution around the indentation was calculated based on the strain gradient theories to reveal the micro-mechanism of plastic deformation. The results indicate that the elastic modulus and hardness for α phase are 129.05 GPas and 6.44 GPa, while for β phase, their values are 109.80 GPa and 4.29 GPa, respectively. The residual Mises stress distribution around the indentation is relatively heterogeneous and significantly influenced by neighboring soft β phase. The region with low residual stress around the indentation is accompanied with markedly high 〈a〉 type and prismatic-GND density.