Production scale processing of a new intermetallic NiAl–Ta–Cr alloy for high-temperature application: Part II. Powder metallurgical production of bolts by hot isostatic pressing

A series of cylindrical bolts of 80 mm diameter and 115 mm height each weighing about 3.5 kg were produced by hot isostatic pressing (HIP) from pre-alloyed powder of the new intermetallic NiAl–Ta–Cr alloy for high-temperature application with nominal composition 45 Ni, 45 Al, 7.5 Cr and 2.5 Al (at.%). The HIP parameters (temperature, pressure, and time) were chosen according to production scale processing conditions for obtaining specific microstructures. To avoid reactions between the NiAl–Ta–Cr alloy and the Ni capsule, a special coating technique was employed. The microstructure of the compacts was characterised by light optical and scanning electron microscopy and the compositions of the constituent alloy phases were determined by energy dispersive analysis. The temperature dependence of the 0.2% yield stress and the stress and temperature dependence of creep were checked and compared with those of the corresponding laboratory scale material.