Ni–(Zr/Hf)–(Nb/Ta)–Al bulk metallic glasses with high thermal stabilities

Thermal stability is a critical consideration in the application of metallic glasses as hydrogen separation material. The development of new Ni-based bulk metallic glasses (BMGs) with enhanced thermal stability is desirable. The present work investigated the alloying effects of refractory metals Hf and Ta on the Ni60Zr20Nb15Al5 bulk metallic glass. Two serial alloys, namely, Ni60Zr20 − xHfxNb15Al5 (x = 0∼20 at.%) and Ni60Zr20TayNb15 − yAl5 (y = 0∼15 at.%), were investigated in the present work. The addition of Hf or Ta was revealed to be effective in improving the thermal stability of the basic alloy, while the glass-forming ability of the alloy is slightly reduced resulting from the addition of Hf or Ta. The possible mechanism of these alloying effects is discussed.