Experimental and numerical investigation of laser-assisted in situ consolidation of CF/PEEK laminates at elevated tool temperature

The inherently rapid cooling in laser-assisted tape placement-based additive manufacturing limits the development of optimised microstructures in fibre-reinforced thermoplastic composites. This study investigates the use of an elevated tool temperature (200 ◦C) within the matrix crystallisation window, together with active control of the peak process temperature, to tailor the microstructure and mechanical performance of carbon fibre/polyetheretherketone (CF/PEEK) laminates. Thermo-mechanical modelling reveals a shift in the hottest region from the incoming tape to the substrate, reducing the temperature difference from ~ 160 ◦C (unheated) to < 10 ◦C (200 ◦C). This effect promotes more uniform thermal histories, leading to reduced void content, increased spherulite size, and enhanced crystallinity. At the fibre–matrix interface, the porous interphase observed in the unheated condition is replaced by a nanoscale crystallised layer with intermediate elemental composition under the heated-tool condition, contributing to an ~ 20 % increase in interfacial shear strength. These microstructural changes lead up to a 40 % increase in interlaminar shear strength while retaining a high Mode I fracture toughness, exceeding that of autoclave-processed laminates. The results demonstrate that the approach proposed provides an effective route for tailoring the processing-structure–property relationship in LATP, thereby enabling a favourable strength-toughness balance without altering the placement parameters.