Richard M. Andrews

Design and tailoring of Ni–Sn–W composites for bonded abrasive applications

Abstract The combination of properties ideal for metal bonds in abrasive products can rarely be achieved in a monolithic material. This research demonstrates a successful approach for producing a composite bond with higher elastic modulus without a significant increase in wear resistance, by taking advantage of the reaction between matrix and reinforcement to produce intermetallics. Composites comprised of a Ni–Sn matrix with continuous W fiber and/or W powder dispersoid were prepared by powder metallurgy methods. Composite specimens densified by hot pressing were characterized with a combination of scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analyses, measurements of wear resistance, and measurements of Youngs modulus and hardness by both bulk and nanoindentation methods. A significant stiffening effect was observed; the elastic modulus of the composites was up to 30% greater than that predicted by a rule of mixtures based on the moduli of the unreacted fiber and matrix constituents alone. As desired, the wear resistance of the composite was approximately equal to that of the Ni–Sn matrix. One contribution to this combination of properties is believed to be the high elastic moduli and likely low fracture toughness of the Ni–W and Ni–Sn intermetallics that are formed. Properties of the Ni–Sn–W composites are contrasted with those of a Ni–Sn matrix reinforced with WC particulate, where no reaction occurs at the interface.