Feasibility analysis of neutron diffraction in NiCrBSi hardfacing layer

Using the hot isostatic press diffusion bonding method, a 5 mm thick NiCrBSi hardfacing layer (Ni balance, 17.32% Cr, 3.45% B, 4.51% Si, 0.70% C, 4.50% Fe, all in wt.%) was successfully deposited on stainless steel. A solid-liquid coexistence heat treatment (1000 ℃, holding 30 min, air cooling) was designed to solve micro-hardness variations and presence of pores and primary particle boundaries (PPBs). Comparing with microstructures of the as-HIP diffusion bonded and heat-treated hardfacing layers, significant homogeneity of microstructures, disappearance of pores and PPBs were observed. Meanwhile, complex phase transformation occurred, with fine-grained Ni, Ni3Si, Ni3B, CrB and Cr7C3 in the as-HIP diffusion bonded hardfacing layer and large-grained Ni, Ni3Si, Ni3B, CrB, Cr7C3 and other phases in the heat treated hardfacing layer. The proposed in-situ high-temperature neutron experiment is to develop the scientific basis and fundamental understanding of phase transformation by means of solid-liquid co-existence heat treatment. Prior to this, it is necessary to conduct feasibility analysis experiment as our sample contains boron. The feasibility analysis experiment will use samples with different thickness (2 mm, 3 mm, 4 mm, 5 mm) to obtain neutron diffraction spectrums at room temperature, and then determine the most suitable sample thickness for in-situ high-temperature neutron experiment.