Ball milling method to form ceramically coated welding tool

A method using ball milling to form a ceramically-coated friction stir welding tool having a cylindrical, conical or triangular tip, and a shoulder, comprising:

• forming a composite of a ball-milled tungsten-rhenium alloy and hafnium carbide particles, by:
• ball-milling a tungsten-rhenium alloy for no more than 25 hours to form a first powder, wherein a concentration of rhenium is in the range of 20 to 30 wt %, relative to the total weight of the tungsten-rhenium alloy;
• mixing hafnium carbide particles with the first powder to form a second powder, wherein a concentration of hafnium carbide particles in the second powder is in the range of 1 to 15 vol %, relative to the total volume of the second powder;
• ball-milling the second powder for no more than 15 hours to form a third powder;
• and
• spark-plasma-sintering the third powder at a temperature of 1500 to 2000° C. for no more than 10 minutes to form the composite of the ball-milled tungsten-rhenium alloy and hafnium carbide particles, wherein the ball-milled hafnium carbide particles are dispersed within the ball-milled tungsten-rhenium alloy, and wherein the ball-milled tungsten-rhenium alloy has a crystallite size of no more than 100 nm;
• coating the composite with a lubricant;
• extruding the composite to form an extruded article;
• then
• at least partially removing the lubricant from the extruded article;
• then
• coating the extruded article with a ceramic to form the ceramically-coated friction stir welding tool.