Crystallographic orientation relationships among η-Ni₃Ti precipitate, reverted austenite, and martensitic matrix in Fe-10Cr-10Ni-2W maraging alloy

Abstract

The precipitation and reversion behavior in Fe-10Cr-10Ni-2W maraging alloy during aging treatment were investigated. The fine rod-shaped η-Ni₃Ti phases were observed to be precipitated having two specific orientation relationships, termed as type I and type II orientation relationships, with martensitic matrix. The reverted austenite phases were also observed, in addition to η-Ni₃Ti precipitates which have two specific orientation relationships known as Kurdjumov-Sachs (K-S) orientation relationship and Nishiyama-Wassermann (N-W) orientation relationship, with the martensitic matrix during aging at a temperature above 550 ‡C. By analyzing the observed electron diffraction patterns and computer-simulated electron diffraction patterns, unified orientation relationships among the martensitic matrix, η-Ni₃Ti precipitate, and reverted austenite phase were suggested. Two types of unified orientation relationships, named as K-S type and N-W type, were found to coexist as follows:

$$K - S{\mathbf{ }}type:{\mathbf{ }}(100)_{\alpha '} ||(00 \cdot 1)_{\eta ^1 } ||(111)_\gamma ;{\mathbf{ }}[1\bar 11]_{\alpha '} ||[11 \cdot 0]_{\eta ^1 } ||[10\bar 1]_\gamma $$

$$N - W{\mathbf{ }}type:{\mathbf{ }}(100)_{\alpha '} ||(00 \cdot 1)_{\eta ^2 } ||(\bar 111)_\gamma ;{\mathbf{ }}[001]_{\alpha '} ||[2\bar 1 \cdot 0]_{\eta ^2 } ||[0\bar 11]_\gamma $$