Q1: Principal alloying elements of cast tool alloys which have very high wear resistance & high temperature strength are

ANS:A - cobalt, chromium & tungsten,

The principal alloying elements of cast tool alloys that exhibit very high wear resistance and high temperature strength are cobalt, chromium, and tungsten. Explanation:

1. Cobalt (Co): Cobalt is often used in tool alloys due to its ability to improve strength, hardness, and wear resistance at high temperatures. It also contributes to the alloy's resistance to corrosion and oxidation.
2. Chromium (Cr): Chromium enhances the hardness, wear resistance, and corrosion resistance of tool alloys. It forms carbides with other elements, contributing to the alloy's high-temperature strength and wear resistance.
3. Tungsten (W): Tungsten is a key alloying element in high-speed and tool steels due to its high hardness, wear resistance, and ability to retain strength at elevated temperatures. It forms hard carbides, which contribute to the alloy's wear resistance and high-temperature strength.