Interface Characterization of Ni/Al Bimetallic Explosively Welded Plate Manufactured with Application of Exceptionally High Detonation Speed

Abstract

The investigation is dedicated to the detailed microstructure characterization of explosively welded clads, in which, exceptionally and for cognitive purposes, a very high detonation speed of about 2800 m/s was used to manufacture bimetallic aluminum-nickel plates. The study involves detailed microstructural characteristics of the bonded zone at micro and nano level, especially focused on the expanded melted regions consisted mostly of Al3Ni, Al3Ni2 and AlNi phases. In situ heating experiment in transmission electron microscope allowed observing microstructure transformation revealing that additionally present metastable Al9Ni2 phase was transformed to Al3Ni and Al3Ni2. Microhardness measurements across the welded zone showed the increase of the microhardness of nickel alloy plate from 153 up to 170 HV when approaching to the Ni201/A1050 interface, while the value for aluminum plate was of 45 HV. Within the melted zones the microhardness was found to be 135 HV and it enormously increased to 850 HV after annealing of the sample at 500 °C. This change was due to the transformation of the interface region from the waves with the melted zones into the continuous layers of two intermetallic phases: Al3Ni and Al3Ni2. The second phase grew at the expense of the Al3Ni.