Effects of test environment and grain size on the tensile properties of L12-ordered (Co,Fe)3V alloys

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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Original languageEnglish
Pages (from-to)146-152
Journal / PublicationMaterials Science and Engineering A
Issue number1-2
Publication statusPublished - 15 May 1992
Externally publishedYes


The influence of test environment, grain size and heat treatment on the tensile properties and fracture behavior of L12-ordered (Co78Fe22)3V and (Co85Fe15)3V alloys was studied at room temperature. The tensile ductility depends strongly on test environments; the elongation decreases in the sequence of oxygen, vacuum, air and distilled water. The loss in elongation is accompanied by a change in fracture mode from transgranular to intergranular. When tested in oxygen or vacuum, (Co78Fe22)3V specimens exhibited predominantly transgranular fracture, while (Co85Fe15)3V specimens exhibited essentially intergranular fracture. Grain refinement of (Co78Fe22)3V resulted in a ductility improvement in air, while such a beneficial effect of grain refinement was not observed in (Co85Fe15)3V. These results suggest that: (1) (Co,Fe)3V alloys exhibit a moisture-induced hydrogen embrittlement and (2) grain boundaries are more intrinsically brittle in (Co85Fe15)3V than in (Co78Fe22)3V. The presence of a brittle hexagonal phase is suggested to be the reason for the observed grain-boundary brittleness in (Co85Fe15)3V. © 1992.