10. The aluminum alloy filler metal rod ER4043, widely used in GTÁW, also contains __ a. iron b. flux c. silicon d. tungsten

The correct answer is c. silicon.<br /><br />The aluminum alloy filler metal rod ER4043, commonly used in Gas Tungsten Arc Welding (GTAW), contains silicon as one of its components. Silicon is added to the alloy to improve its weldability and mechanical properties. It helps to reduce the oxidation of the weld pool and enhances the strength and hardness of the weld metal. Silicon also contributes to the formation of a stable oxide layer on the surface of the weld, which protects the molten metal from further oxidation.