Molecular Dynamics Study on Adhesion of Various Ni/Al Interface for Ni- Plated Aluminum Alloys

K Yashiro and K Nimura and K Naito, JOURNAL OF THE JAPAN INSTITUTE OF METALS AND MATERIALS, 83, 198-206 (2019).

DOI: 10.2320/jinstmet.J2019005

As a fundamental study on the adhesion of Ni-plating on aluminum alloys, various molecular dynamics simulations are performed on Ni/Al infinite laminate structure under tension, by changing mixing concentration of Ni and Al at the interface. The adhesion shows the highest at the perfect(001) Ni/Al interface while it decreases with the rate of random mixing in Ni/Al phases(10%, 30% and 50% substitution in each phase). Especially the 50% substitution in Al phase remarkably decreases the adhesion compare to the same substitution in Ni phase. The(111) interface shows weaker adhesion than(001) for perfect Ni/Al interface, and the substitution doesn't largely affect to the adhesion reduction as the(001) interface. The(001) interfaces are always ruptured in brittle manner near the interface in Al side, and few Ni atoms are observed on the fracture surface. The(111) interfaces shows shear-lip breakage by void formation and growth in Al side further away from the interface. We obtained simple conclusion that the Ni/Al interface is inherently strong and the delamination never takes place at the interface, since the surface energy and elastic coefficients of Ni are much larger than Al. The large reduction of adhesion by atom mixing in the(001) interfaces can be explained with the initial misfit at the interface while it doesn't largely affect to the close-packed(111) interface. Assuming various phenomena in real Ni-plating, we also performed simulations with Ni3Al and NiAl interlayer,(001)-(110) surfaces combination; and all results in the same story above mentioned. Finally, we performed calculations on Ni-P system, and revealed that the surface energy of amorphous Ni-P is close to that of Al. Thus interfacial delamination can be occurred between the amorphous Ni-P plating and aluminum base.

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