FIB-etching of polymer/metal laminates and its effect on mechanical performance

Area of Science:

• Materials Science
• Polymer Science
• Surface Engineering

Background:

• Investigating polymer/metal adhesive interfaces is crucial for material performance.
• Understanding strain-induced failure mechanisms in laminates is key for design.
• Previous studies lacked in-situ observation of interface behavior under uniaxial strain.

Purpose of the Study:

• To investigate the adhesive interface behavior in polyethylene terephthalate/steel laminates under uniaxial strain.
• To characterize the initiation and propagation of crazes in PET at the polymer/metal interface.
• To evaluate the influence of focused ion beam (FIB) preparation on the mechanical properties and interface behavior of the laminate.

Main Methods:

• In situ straining of polymer/metal laminate cross-sections within a scanning electron microscope.
• Focused ion beam (FIB) milling to prepare cross-sections perpendicular to the interface.
• High-resolution scanning electron microscopy (SEM) imaging during mechanical testing.

Main Results:

• Steel glide steps at the interface induced traction, initiating crazes in polyethylene terephthalate (PET).
• Crazes propagated along the free surface of the PET layer, a novel observation in this configuration.
• Focused ion beam etching significantly altered PET mechanical properties, particularly toughness.
• The effect of FIB treatment on mechanical properties varied between pre-strained and in situ strained samples.

Conclusions:

• In situ straining reveals unique craze initiation and propagation mechanisms at polymer/metal interfaces.
• Focused ion beam preparation methods can significantly influence the observed mechanical behavior of polymer/metal laminates.
• Careful consideration of FIB effects is necessary when interpreting mechanical property data from prepared samples.