ＷＣ‐（０‐１６）ｍａｓｓ％Ｃｒ３Ｃ２‐１５ｍａｓｓ％Ｎｉ 超硬合金の組織と機械的特性及び腐食特性

Abstract

Microstructures, some mechanical properties and electrochemical corrosive behavior of WC-(0-16)mass% Cr3C2-15 mass% Ni alloys were studied as a function of carbon and Cr3C2 contents of these alloys.It was found that solid solubility of Cr into γphase (Ni phase) of WC-Cr3C2-15 mass%Ni alloy was about 2% and 4mass% Cr3C2 in high and low carbon alloys, respectively. In the range of the excess Cr3C2 content more than the solubility limit of Cr, some phases of WC+γ+M2C+M6C (θ) (M =(Cr, W, Ni), M6C=θphase), WC+γ+M2C, WC+γ+M2C+M3C2, WC+γ+M3C2 to WC+γ+M3C2+FC appeared with increasing carbon content in the alloys.Hardness of the alloys increased with increasing the amount of Cr3C2. On the other hand, the transverse rupture strength reached the peak value at the solubility limit of Cr because of the finer grain size of WC by the effect of grain growth inhibition. More than the solubility limit of Cr, the transverse-rupture strength decreased with increasing the amount of Cr3C2, which was considered to be caused by crystallized MxCy acting as fracture source.On the anodic polarization curve in 3%NaCl solution, corrosive current density of these alloys decreased with increasing the amount of Cr3C2 within the solubility limit of Cr in yphase, but it was saturated more than the solubility limit of Cr.