Pishyar Science & Technology Corporation (Pishst)
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Single-Crystal Performance —
Engineered for Extreme Conditions
The elimination of grain boundaries in single-crystal structures can significantly enhance the performance of advanced materials under demanding operating conditions. By controlling crystal orientation, solidification, alloy chemistry, and processing conditions, critical mechanical, physical, and high-temperature properties can be substantially improved.
In the experimental results shown here, advanced directionally controlled structures demonstrated more than a threefold increase in creep elongation under one of the tested temperature and stress conditions compared with conventional cast blades.
These improvements are particularly important for components exposed to high temperatures, sustained mechanical loads, thermal cycling, oxidation, and corrosive environments, such as gas and steam turbine components.
Precision in crystal growth creates precision in performance.
Creep elongation comparison of three blade conditions—Conventional Cast (CC), Preliminary DS, and Improved DS—tested under two different temperature and stress conditions (982°C/152 MPa and 760°C/586 MPa). The results demonstrate that the improved directionally solidified structure achieved more than a threefold increase in creep elongation compared with conventional cast blades under one of the tested conditions.
Rupture Life and Service Durability
Experimental results show that directionally solidified (DS) blades achieved more than twice the rupture life of conventional cast (CC) blades under the tested conditions. In actual turbine service, however, component life is also affected by oxidation, corrosion, thermal cycling, and other environmental damage mechanisms. Grain boundaries can provide preferential paths for degradation and damage, particularly at high temperatures. Single-crystal structures eliminate grain boundaries, removing an important potential path for grain-boundary-related degradation and contributing to improved durability in severe turbine operating environments.
Grain-Boundary Corrosion
and Service Life
In real turbine operating conditions, component life is influenced not only by creep and mechanical stress, but also by oxidation and corrosion. Studies of polycrystalline turbine blades have shown that grain boundaries can provide preferential paths for corrosion and oxidation, particularly near blade tips. By eliminating grain boundaries, single-crystal structures remove this potential path of grain-boundary degradation, contributing to improved durability under severe high-temperature service conditions.
