Fantin, A.; Manzoni, A.M.; Springer, H.; Kamachali, R.D.; Maaß, R.: Local lattice distortions and chemical short-range order in MoNbTaW. Materials Research Letters 12 (2024), p. 346-354
10.1080/21663831.2024.2326014
Open Access Version
Abstract:
Extended X-ray absorption fine structure (EXAFS) conducted on an equiatomic MoNbTaW bcc medium-entropy alloy that was annealed at 2273 K reveals unexpectedly small 1st and 2nd shell element-specific lattice distortions. An experimental size-mismatch parameter, 𝛿exp, is determined to be ca. 50% lower than the corresponding calculated value. Around W, short-range order (SRO) preferring 4d elements in the 1st and 2nd shells persists. A Nb-W ordering is found, which is reminiscent of ordering emerging at lower temperatures in the B2(Mo,W;Ta,Nb)- and B32(Nb,W)-phases. With high-temperature ordering preferences in fcc also foreshadowing low-temperature phase, these findings suggest a general feature of high-temperature SRO.