Effect of Al Content on Phase Constitution and Tensile Properties of Ti-13mass percent Cr-lmass percent Fe-Al Alloys

摘要

The influence of Al content on phase constitution and tensile properties of Ti-13mass percent Cr-lmass percent Fe-Al alloys was investigated by measurement of electrical resistivity and Vickers hardness, X-ray diffractometry (XRD) and tensile test. For all solution treated and quenched (STQed) specimens, only beta reflection was detected by XRD. Resistivity at room and liquid nitrogen temperatures increased monotonically with Al content. Vickers hardness kept almost the same value as STQed specimen up to 3.0mass percent Al and men increase with Al content In the isochronal heat treatment, two minima of resistivity ratio (PLN/PRT) were observed at 623K and 823K, respectively. The former is due to the precipitation of isothermal omega phase and the latter is alpha precipitation. The temperature of resistivity minimum attributing to omega phase precipitation gradually increases with Al content. In the alloys with 4.5mass percent Al and more, the minimum of resistivity associated with omega precipitation disappeared and the minimum caused by a precipitation remained. It is considered that Al content above 4.5msss percent was suppressed isothermal omega precipitation and enhanced a precipitation. In STQed alloys, tensile strength increased slightly with Al content and elongation at fracture kept almost constant value. Ti-13mass percent t Cr-lmass percent Fe-Al alloys in STQed state without isothermal omega precipitation had the comparable tensile properties to Ti-22mass percentV-4mass percent Al, one of the most popular beta titanium alloy.