b'perform macro-scale tensile testingat University of Nebraska-Lincoln to calibrate the localization criterionby tension testing at room for predicting the ductility at thetemperature, 500 C, and 700 C, macro-scale. respectively. When the temperature The project selects FeCrAl as thewas increased to 700 C, the stress primary testing materials sincedecreases immediately after yield, FeCrAl alloys have attractedthere is no strain hardening. Slip increased interests in the nuclearresistance for {112} and {110} slips community as a promising candidateare measured by using micropillars for accident tolerant fuel claddingat University of Nebraska-Lincoln for light water reactors. Along withand Purdue University.There is its wide applications and excellentno obvious size effect as the pillar diameter is greater than 5.5 m. properties, we aim at developing anThe critical resolved shear stress of integrated theoretical, modeling, andFeCrAl single crystals associated experimental platform (Figure 1) thatwith dominant slip system of {110} enables prediction of the macro- 111 and {112} 111 are 220 MPa ductility of FeCrAl alloys based onand 230 MPa at room temperature, micro-scale mechanical tests. The142 and 141 MPa at 200C, 137 and technologies and modeling capa- 139 MPa at 350 C, and 115 MPa for bilities developed from this project,both slip systems at 500 C.however, are generally applicable to alloys other than FeCrAl. ThisHardening behaviors of micropillars project will establish such a frame- were investigated at University of work that combines mechanicalNebraska-Lincoln by using micro-testing and modeling techniques atpillars with specific orientations various length scales to understandwhich favor the type and number the mechanical properties of smallof activated slip systems. The strain specimens and predict the strengthhardening rates derived from these and ductility of large-scale specimenstests clearly indicated that the weakest with similar internal microstructureshardening is associated with pillars and microchemistry. The project willwith one activated slip system, the have direct impact on understandinglargest hardening is observed in pillars the mechanical behavior of a suitewith multiple activated slip systems. of irradiated small-scale metallicThe critical strain for reaching a materials for applications in variousstable strain hardening rate increases nuclear reactors. with the number of activated slip systems. For the bi-crystal pillars, Accomplishments: the strain hardening rate is related Temperature dependence of theto the geometrical compatibility mechanical property of polycrystal- factor, the higher the factor is, the line FeCrAl alloys was evaluatedlower the strain hardening rate is.46 2022|AFC ACCOMPLISHMENTS'