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Abstract: Thermal tests exposed V–4Cr–4Ti in static liquid lithium at 700 and 800°C for 250, 500, and 1000h. 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 1000h exposures at both 700 and 800°C. [Copyright &y& Elsevier]

Abstract: Because of their superior high temperature strength and corrosion properties, a set of Ni-base alloys has been proposed for various in-core applications in Gen IV reactor systems. However, irradiation-performance data for these alloys is either limited or non-existent. A review is presented of the irradiation-performance of a group of Ni-base alloys based upon data from fast breeder reactor programs conducted in the 1975–1985 timeframe with emphasis on the mechanisms involved in the loss of high temperature ductility and the breakdown in swelling resistance with increasing neutron dose. The implications of these data for the performance of the Gen IV Ni-base alloys are discussed and possible pathways to mitigate the effects of irradiation on alloy performance are outlined. A radical approach to designing radiation damage-resistant Ni alloys based upon recent advances in mechanical alloying is also described. [Copyright &y& Elsevier]