High temperature interaction between molten Ni50Al50 alloy and ZrB2 ultra-high temperature ceramics

TL;DR

This study investigates the high-temperature wetting and interfacial reactions between molten Ni50Al50 alloy and ZrB2 ceramics, revealing rapid wetting, reactive infiltration, and formation of interfacial layers relevant for ceramic joining.

Contribution

It provides the first detailed experimental analysis of Ni50Al50 alloy's interaction with ZrB2 at high temperatures, highlighting rapid wetting and complex interfacial phenomena.

Findings

Ni50Al50 rapidly wets ZrB2 at 1688°C

Formation of Ni-enriched interfacial layer

Reactive infiltration with Al2O3 formation

Abstract

In this work, Ni50Al50 alloy is taken into consideration as potential brazing material for joining ZrB2 ultra-high temperature ceramic. The results of experimental study on high temperature interfacial phenomena between molten binary Ni50Al50 alloy and polycrystalline ZrB2, are shown. A sessile drop method combined with a capillary purification procedure was applied to investigate the wetting behavior of Ni50Al50/ZrB2 couple during holding for 400 seconds at temperature of 1688{\deg}C (i.e. at T=1.02Tm). It was found that the molten Ni50Al50 rapidly wets and spreads over the surface of ZrB2, while involved reactive infiltration into the solid substrate allowed reaching a final contact angle of ~0{\deg} in 250 sec. The wetting kinetics was much faster than that reported in the literature for Cu, Ag or Au tested at T=1.05Tm. The solidified couple was subjected to SEM/EDS microstructural characterization in order to reveal a course of interfacial phenomena. The results point towards (I) an existence of Ni-enriched Ni-Al/ZrB2 surface interfacial layer; (II) a formation of infiltration zone assisted by reactively formed Al2O3 due to a reaction with Al-rich melt and (III) a partial transfer of ZrB2 phase to Ni50Al50 alloy by a dissolution/precipitation mechanism.