Effect of Zr, B and C additions on the ductility of molybdenum

Through the addition of Zr, Al, C and B at the parts per million level to molybdenum, a significant improvement in ductility of a molybdenum weldment has been produced. This improvement approaches 20% ductility in gas–tungsten arc weldments in 4.8-mm-thick plate compared to the traditional 3% ductility. This improvement has been achieved by improving the normally low fracture stress of grain boundaries. Atom probe tomography revealed segregation of zirconium, boron and carbon and the depletion of oxygen and nitrogen at the grain boundaries in the base metal.