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Theoretical predictions make the Bi x Pd 1− x system a promising candidate for studying the possibility of amorphization by an enforced extension of the solubility into a metastable regime. By quench-condensation of Bi 30 Pd 70 , the existence of a previously unknown amorphous (a–) phase is proven, which above 520 K crystallizes into the monoclinic Bi 2 Pd 5 phase. Ar + -irradiation of this crystalline phase at low temperatures leads back into the a-phase in accordance with a general amorphization rule. Experimentally, this behaviour is demonstrated by applying in situ resistance measurements and ex situ XRD. A surprising result is found for supersaturated Pd 70 Bi 30 solid solutions, which can be prepared by exploiting interface reactions in Pd/Bi multilayers. Ion irradiation performed on these cubic metastable solid solutions under exactly the same conditions as above, result only in a segregation of the surplus Bi towards the equilibrium solubility limit. No irradiation induced amorphization can be obtained starting with a stable or metastable cubic solid solution. |
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