Femtosecond-laser tailoring interfaces of injection molded metal-plastic hybrids: shear strengths and failure modes under pull-push loadings

• Metal-plastic hybrids (MPHs) interface states were systematically tailored by femtosecond-laser. • Mechanisms of interface and matrix failure modes were revealed and discussed. • Two critical micro-pattern depths influencing MPHs’ shear strength and failure mode were determined. Metal-plastic hybrids (MPHs) gain wide applications thanks to their high specific strength beneficial to lightweight design for industrial products. This work aims to tailor MPHs’ interface states in order to improve bonding strengths under pull-push loadings associated with various application scenarios. To systematically reveal the interface influencing factors such as micro-pattern size, distribution, morphology, and chemical bond, femtosecond-laser treated aluminum and titanium alloys were bonded to polyphenylene sulfide to form MPHs (Al/PPS and Ti/PPS) via injection molding, and both pull and push-loading shear strengths were investigated. Interesting cauliflower-like deep patterns with laser-induced periodic surface structures formed for the aluminum alloy resulting in higher shear strength, while shallow and smooth wave-like patterns appeared for the titanium alloy. However, with the same micro-pattern nominal size/distribution, Ti/PPS possessed significantly higher shear strength (Max. 10.5 MPa). Moreover, critical micro-pattern depths, d c1 of ∼40 μm, and d c2 of ∼300 μm were determined under the pull and push loadings, respectively. This study provides guidelines for designing and manufacturing lightweight MPHs for various applications.