Microstructure control in high Ti NbTi alloys

The microstructures of five high-Ti NbTi alloys (Nb49-62-wt.%Ti) and a ternary Nb-54-wt.%Ti, 4-wt.%Zr alloy have been observed following heat treatments of 80 h at 420 degrees C at prestrains of between 8.3 and 12.6. It was found that increasing prestrain suppressed the formation of deleterious Widmanstatten alpha -Ti and omega phases and that the higher the Ti content, the higher the prestrain required for elimination of these forms of precipitation. The Zr addition increased the precipitation rate and reduced the precipitate size without promoting the formation of Widmanstatten alpha -Ti or omega .<
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