Journal of Materials Research

Rapid Communications

A new high-strength spinodal alloy

James A. Hannaa1 c1, Ian Bakera1, Markus W. Wittmanna1 and Paul R. Munroea2

a1 Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire 03755

a2 Electron Microscope Unit, University of New South Wales, Sydney, NSW 2052, Australia

Abstract

Preliminary investigations of a new high-strength alloy of composition Fe30Ni20Mn25Al25 (at.%) are described in this paper. The as-cast alloy consisted of a periodic two-phase microstructure of interconnected, ∼50-nm-wide rods with fully coherent {100} interfaces, strongly suggestive of formation by a B2 to [(B2 + body-centered cubic (bcc)] spinodal decomposition. The (Ni,Al)-rich B2 and (Fe,Mn)-rich bcc phases differed in lattice parameter by <0.5%. Hardness and yield strength of the as-cast alloy were found to be approximately 500 VPN and 1500 MPa, respectively, and increased by more than 50% after annealing at 550 °C for several days. (Fe,Mn)-rich precipitates with a β–Mn structure were observed in the annealed material.

(Received January 15 2005)

(Accepted February 02 2005)

(Online publication April 2005)

Key Words:

  • Intermetallic alloys;
  • Mechanical properties;
  • Nanoscale

Correspondence:

c1 Address all correspondence to this author. e-mail: James.A.Hanna@Dartmouth.edu

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