It has been shown that Ni{sub 3}Si displays excellent mechanical properties when Ti is added. However, the Ni{sub 3}(Si,Ti) alloy has been known to exhibit a so-called environmental embrittlement. This embrittlement involves the generation of atomic hydrogen produced by a reaction of Si and/or Ti with moisture in air, and the subsequent penetration along grain boundaries, resulting in severe hydrogen-induced embrittlement. On the other hand, it has been shown by Takasugi et al. that boron doping almost completely suppresses the environmental embrittlement of this alloy. Similar embrittlement and beneficial effect of boron have been observed in Ni{sub 3}Si alloys. It has been suggested that boron probably enriches on grain boundaries (actually detected by field ion microscopic observations (FIM)) and prohibits harmful action of hydrogen atoms at grain boundaries. However, no direct correlation between the embrittlement and the grain boundary composition, particularly boron concentration, has been reported for this alloy. In this work, the authors used a Ni{sub 3}(Si,Ti) alloy unintentionally charged with boron, whose mechanical properties have been reported previously using different heat treatments and in different test conditions at room temperature. The Ni{sub 3}(Si,Ti) alloys prepared in this work were quenched from various temperatures, and thereby are expected tomore » have different concentrations of boron (and/or constituent elements) at grain boundaries and different mechanical properties.« less