High-temperature mechanical behavior of Ti-6Al-4V alloy and TiCp/Ti-6Al-4V composite

摘要

Mechanical behaviors at 538 0C, including tensileand creep properties, were investigated for both the Ti-6A1-4Valloy and the Ti-6A1-4V composite reinforced with 10 wt pctTiC particulates fabricated by cold and hot isostatic pressing(CHIP). It was shown that the yield strength (YS) and ultimatetensile strength (UTS) of the composite were greater than thoseof the matrix alloy at the strain rates ranging fromapproximately 10-5 to 10 -3 S-1 However, the elongation of thecomposite material was substantially lower than that of thematrix alloy. The creep resistance of the composite was superiorto that of the matrix alloy. The data of minimum creep strainrate vs applied stress for the composite can be fit to a power-lawequation, and the stress exponent values of 5 and 8 wereobtained for applied stress ranges of 103 to 232 MPa and 232 to379 MPa, respectively. The damage mechanisms were differentfor the matrix alloy and the composite, as demonstrated by thescanning electron microscopy (SEM) observation of fracturesurfaces and the optical microscopy examination of the regionsadjacent to the fracture surface. The tensile-tested matrix alloyshowed dimpled fracture, while the creep-tested matrix alloyexhibited preferentially interlath and intercolony cracking. Thefailure of the tensile-tested and creep-tested composite materialwas controlled by the cleavage failure of the particulates, whichwas followed by the ductile fracture of the matrix.