3D auxetic structures A380 alloy ANOVA AlFeSi phase Business strategy Ca ECAP Fe-based amorphous alloys Manufacturing industries OFHC copper C102 PCBN tool Q-learning amorphous alloys assisted machining chip formation coating technology cutting forces decision-support system deformation mechanism difficult-to-machine drilling grain size gray cast iron high-frequency PCB hot filament chemical vapor deposition just-in-time learning machine learning metallic materials micro assembled micro-cutting