Dose dependence of true stress parameters in irradiated bcc, fcc, and hcp metals

Dose dependence of mechanical properties in tantalum and tantalum alloys after low temperature irradiation

“…Both deformation maps indicate that PIS and FS are nearly independent of dose, while YS is strongly dose dependent. This dose independence of PIS and FS was observed in many other materials [11][12][13][14]. At room temperature the PIS values of pure tantalum metals were in the range 270-300 MPa, and those of the Ta-1W alloy are in the range 450-490 MPa.…”

“…Comparing the sizes of regions of deformation modes, the mode maps for the tantalum materials are characterized by a relatively large plastic instability region and a narrow uniform deformation region, which should be due to large necking ductility and relatively low strain-hardening rate (this usually results in low uniform ductility), respectively. This feature is common for many body-centered cubic and hexagonal close packed metals [13].…”

“…A macroscopic deformation mode map in true stress-dose space can be used for predicting the performance of a material in irradiation environments. Building such a deformation mode map requires true stress data such as yield stress, plastic instability stress (PIS), and fracture stress (FS) to define boundaries between the deformation modes [13]. The YS and PIS values are directly obtained from the engineering tensile data while the FS value is calculated from engineering fracture stress data through a model described elsewhere [11][12][13].…”

“…The plastic instability stress is the true stress version of ultimate tensile strength. The calculation of FS is based on a linear strain-hardening model for necking deformation, where the strain-hardening rate remains unchanged during instable deformation and is approximately the same as the plastic instability stress [13,14].…”

“…FS will decrease with dose if the material is affected by any radiation-induced embrittlement mechanism [13]. During embrittlement, the material will experience brittle failure when the YS line meets with the FS line.…”