A concise review of Ti64 nanoindentation and CPFEM modelling approaches

Abstract Ti–6Al–4V’s dual-phase ( $$\upalpha +\upbeta $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>α</mml:mi> <mml:mo>+</mml:mo> <mml:mi>β</mml:mi> </mml:mrow> </mml:math> ) microstructure yields local mechanical behaviors that conventional tests cannot fully resolve. Instrumented nanoindentation delivers spatially resolved hardness, modulus, and creep at micron scales, while crystal plasticity finite-element modeling (CPFEM) translates these data into slip-system insights and component-scale predictions. This review unifies three decades of work on Ti64 nanoindentation and CPFEM, covering fundamental alloy chemistry and microstructures (equiaxed, bimodal, lamellar), advanced indentation protocols (continuous stiffness, spherical tips, high-throughput mapping), and CPFEM developments from phenomenological yield laws to gradient-enhanced, multi-phase simulations reproducing orientation-dependent responses. We spotlight four persisting challenges: defining representative volume elements, capturing size effects via length-scale physics, modeling $$\upalpha /\upbeta $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>α</mml:mi> <mml:mo>/</mml:mo> <mml:mi>β</mml:mi> </mml:mrow> </mml:math> interfacial constraints and Burgers orientation relationships, and managing experimental scatter for robust parameter inversion. We also survey emerging solutions—dense indent grids, in situ lattice-strain validation, and machine-learning-driven calibration—as pathways toward predictive, microstructure-sensitive design of Ti64 components. Graphical abstract