Study of Aging Effects in a Ti-6AL-4V Alloy with Widmanstatten and Equiaxed Microstructures by Non-Destructive Means

When the Ti-6Al-4V alloy is over-aged at 500-600 degrees C, nanometer-sized alpha(2) (Ti3Al) phases can be homogeneously precipitated inside alpha phases, thereby leading to the additional improvement of mechanical properties. The present study was concerned with the effects of over-aging on thermoelectric power (TEP) measurements in a Ti6A1-4V alloy. Widmanstatten and equiaxed microstructures containing fine alpha(2) (Ti3Al) particles were obtaining by overaging a Ti-6A1-4V alloy. Over-aging heat treatments were conducted at 515 degrees C, 545 degrees C and 575 degrees C for different aging times. In order to find out the factors affecting the variation in the TEP, the over-aging samples were examined by optical microscopy (OM) and (SEM) scanning electron microscopy. In particular, we studied the behavior of the physical material property hardness, an important parameter of the Ti-6A1-4V alloy mechanical properties, with respect to the variation in the aging time and temperature. It was found that the TEP measurements reveal an increase in the magnitude of the absolute TEP value of the over-aged Widmanstatten and equiaxed microstructures with regards to the unaged condition for different aging times, with a somewhat higher value at 515 degrees C.