Decrease of yield strength in molybdenum by adding small amounts of Group VIII elements

Abstract

Three-point bend tests at 273 and 223 K were performed to investigate the deformation behavior of molybdenum alloys when adding small amounts of Group VIII elements such as iron, cobalt, nickel or palladium. The results are summarized as follows: (1) The yield strength initially decreased with small additions of Group VIII elements. The yield strength of the Mo–Co, Mo–Ni and Mo–Pd alloys demonstrated a minimum value, though the specific alloy content was different between the alloys. However, the yield strength of the Mo–Fe alloy monotonously decreased with the alloy content. (2) The decrease of the yield strength with small amounts of Group VIII elements is attributed primarily to the difference in the number of (s+d)-electrons between the alloy element and molybdenum. The difference in the atomic size between the alloy element and molybdenum has a positive, though minor, effect on the yield strength.