Solidification shrinkage of Ni–Cr alloys

Ni–Cr superalloy is widely used in casting of critical components in gas-turbine engines. Because of the significant change in density of alloy in mushy state, porosity is likely to arise in the alloy parts due to the solidification shrinkage. On the other hand, because Ni–Cr alloy is very hard and difficult to be machined, the net-shape casting of the alloy is a cheap process. Therefore, it is essential to measure the solidification shrinkage of mushy alloy for obtaining low-cost net-shape casting ingot without inner porosity. However, there have been a few reports on the solidification shrinkage of the liquid Ni–Cr alloy. In this work, the solidification shrinkage of Ni–Cr alloy was calculated by measuring its density using modified sessile drop method. It has been found that, for Ni–(0–24.53)% Cr alloys, the solidification shrinkage value fluctuates in the range of 0.91–2.02% and it tends to increase with increasing Cr concentration in 0–10% Cr. However, for Cr concentration more than 10%, the solidification shrinkage holds on a certain value of 2.00%.