Grain boundary melting of hafnium containing Ni[sub 3]Al intermetallic compounds

Journal Article · Thu Sep 15 04:00:00 UTC 1994 · Scripta Metallurgica et Materialia; (United States)

DOI:https://doi.org/10.1016/0956-716X(94)90224-0· OSTI ID:7244419

Chang, T T; Chuang, T H ^[1]

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1. National Taiwan Univ., Taipei (Taiwan, Province of China). Inst. of Materials Science and Engineering

The Ni[sub 3]Al intermetallic compound possesses the L1[sub 2]-type ordered structure below the melting temperature. Its yield strength has been shown to increase with increasing temperature. Also, it is the principal strengthening phase ([gamma][prime]) of the commercial nickelbase superalloys. However, there exists a serious problem of brittle intergranular fracture in polycrystalline Ni[sub 3]Al. By macroalloying with hafnium, Liu and White showed that the yield stress of Ni[sub 3]Al increases and raises the peak-strength temperature with hafnium additions. Taniguchi et al. found that hafnium alloying effectively decreases the oxidation rate and improves oxide scale adherence. In addition, hafnium additions improved other properties of Ni[sub 3]Al, such as creep resistance and high-cycle fatigue life. Although ternary or quaternary alloying additions have been shown to improve the thermomechanical properties of Ni[sub 3]Al, some alloying elements might segregate to the grain boundary to cause grain boundary melting at elevated temperatures below 1,395 C. The present study shows that the increase of hafnium content decreases the melting temperature of this alloy and, thus, increases the tendency for grain boundaries to melt.

• OSTI ID: 7244419
• Journal Information: Scripta Metallurgica et Materialia; (United States), Journal Name: Scripta Metallurgica et Materialia; (United States) Vol. 31:6; ISSN 0956-716X; ISSN SCRMEX
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
ALLOYS
ALUMINIUM ALLOYS
ELEMENTS
GRAIN BOUNDARIES
HAFNIUM
HAFNIUM ALLOYS
MELTING POINTS
METALLURGICAL EFFECTS
METALS
MICROSTRUCTURE
NICKEL ALLOYS
NICKEL BASE ALLOYS
PHYSICAL PROPERTIES
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENTS
TRANSITION TEMPERATURE