On the short-range orders in spinodal Pd–Ni–P bulk metallic glasses

•Origin of the miscibility gap•X-ray diffraction method•Two characteristic short-range orders

Recently, it was found that undercooled molten Pd–Ni–P undergoes amorphous/liquid spinodal decomposition or equivalently the alloy system has a metastable liquid miscibility gap (MLMG) in its undercooling regime. This is unusual because the alloy system has a negative heat of mixing. In this work, a portion of the MLMG was determined, at 613 and 593 K. The incomplete MLMG obtained differs fundamentally from that of an alloy system with a positive heat of mixing. EDX and X-ray studies show that the MLMG is due to two unique short-range orders.