Alloy softening in group via metals alloyed with rhenium

Chromium and chromium-based alloys: Problems and possibilities for high-temperature service

“…47 Several observations 48,49 have been done to investigate the ductility and strength properties of chromium alloyed with rhenium additions ranging from zero up to 40 at.% and numerous suggestions have been put forward to explain the mechanisms by which rhenium effects this remarkable improvement in the cold ductility of chromium. 50 However, the validity of these suggestions remains unsubstantiated.…”

Low-temperature thermally-activated deformation and irradiation softening in neutron-irradiated molybdenum

“…This phenomenon is also called 'solid solution softening'. The 'alloy softening' effect has been well studied in bcc transition metals, particularly in the refractory VIA group metals Cr, Mo and W [15][16][17][18][19]. It may be used as a possible way to improve low-temperature ductility of refractory metals, such as the so-called 'rhenium ductilizing effect' [19].…”

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

“…Stephens and Witze [17] investigated the hardness change of molybdenum by adding a Group IVA element such as hafnium (Hf), a Group VA element such as tantalum (Ta), a Group VIA element such as tungsten (W), a Group VIIA element such as rhenium, or Group VIII elements such as osmium, iridium and platinum from the viewpoint of the electron configuration. They suggested that the alloy softening phenomenon is correlated with the difference in the number of (s + d)-electrons between the alloy element and molybdenum [12]. For example, only small additions of the element having larger number of the (s + d)-electrons than that of molybdenum should induce a remarkable softening effect.…”

“…One of the most favorable elements is rhenium (Re) that belongs to Group VIIA. Addition of a certain amount of rhenium substantially decreases the yield strength of molybdenum, which is called rhenium softening effect [9][10][11][12][13][14]. The low-temperature ductility of the Mo-Re alloys is generally excellent [15][16][17][18][19][20][21].…”