Effect of micron-sized particles on the crack growth behavior of a Ni-based powder metallurgy superalloy

Abstract

Generally, larger non-metallic inclusions have a negative influence on crack growth resistance due to the stress concentration effects that result from them appearing along the paths of crack growth. The in-situ tensile behavior for dog-bone-shape specimens of a Ni-based powder metallurgy FGH4096 superalloy including micro-sized particles has been investigated. The effect of the micron-sized particles on the initiation and propagation of cracks was studied through the in-situ tensile test. The mechanism of the in-situ tensile process was investigated using molecular dynamics methods. The results showed that the particle inclusions were basically micron-sized, including carbide particles, rare earth inclusions and composite inclusions in the FGH4096 superalloy. The carbide particles cracked themselves but did not become a source of a main crack. Many carbide particles near the main crack paths did not aggravate the propagation of the main crack under tensile behavior. Molecular dynamics simulation results showed that the crack was found to be preferable close of regions of atomic disorder, and a stacking fault area formed during deformation was found to effectively release the stress concentration and delay the occurrence of cracks. Crack initiation and propagation around a notch was also investigated in detail, by combining the experimental and computational results.