The Influence of lithium environment on tensile behavior and microstructure of V–4Cr–4Ti

Thermal tests exposed V–4Cr–4Ti in static liquid lithium at 700 and 800 °C for 250, 500, and 1000 h. Post-exposure examination included chemical analysis of interstitial impurities in V–4Cr–4Ti to monitor impurity transfer, and tensile tests at room temperature and 500 °C. Microstructures were characterized by room-temperature electrical resistivity measurements and transmission electron microscopy. Oxygen was not depleted from V–4Cr–4Ti when nitrogen pickup occurred during lithium exposures. In spite of a significant increase in interstitial impurity concentration, the matrix interstitial solute content was reduced due to precipitation. Plate-shaped precipitates in the matrix and globular precipitates at grain boundaries were formed during lithium exposures at 700 °C, while only globular precipitates were observed at grain boundaries at 800 °C. Increases in strength, decreases in ductility, and reduced dynamic strain aging resulted. Ductility remained high after 1000 h exposures at both 700 and 800 °C.