Microstructure investigations on explosive TiNi(or Ni)/TiC-composite-formation reaction during mechanical alloying

Journal Article · Wed May 01 00:00:00 EDT 1996 · Acta Materialia

DOI:https://doi.org/10.1016/1359-6454(95)00327-4· OSTI ID:247937

Huang, J Y; Ye, L L; Wu, Y K; Ye, H Q ^[1]

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1. Chinese Academy of Sciences, Shenyang (China)

The microstructure of TiNi(or Ni)/TiC composite prepared by mechanical alloying (MA) of elemental Ti, Ni and C powders has been investigated in detail. The result shows that large agglomerates with size 3--10 mm were abruptly formed for Ti{sub 50}Ni{sub 20}C{sub 30}, Ti{sub 40}Ni{sub 40}C{sub 20} and Ti{sub 30}Ni{sub 50}C{sub 20} powders at the milling duration of 3 h 30 min--3h 35 min, which suggests melting of the powders and subsequent quenching has occurred during MA. Transmission electron microscopy shows that spherical TiC grains, lath twin martensite (M) and B2 phase are directly formed after 3 h 35 min MA of Ti{sub 50}Ni{sub 20}C{sub 30} powders. It is also found that there exists definite orientation relationships between M and B2 phases which are very close to those obtained by Otsuka et al. in equiatomic TiNi martensite. The resultant phases are predominantly TiC and M phases with a small amount of B2 phase for Ti{sub 40}Ni{sub 40}C{sub 20}; and Ni and TiC phases for Ti{sub 30}Ni{sub 50}C{sub 20} after 3 h 35 min of MA. The microstructure characteristics of the as-milled materials are very similar to those of melted and solidified ones, which proves that melting of the powders and subsequent quenching has really occurred during the MA process. The authors concluded that MA in Ti{sub 50}Ni{sub 20}C{sub 30}, Ti{sub 40}Ni{sub 40}C{sub 20} and Ti{sub 30}Ni{sub 50}C{sub 20} is not governed by a gradual diffusional reaction, but by a self-sustained high-temperature synthesis (SHS) one. The SHS reaction is believed to be triggered by the release of heat of formation of the TiC phase and ignited by the mechanical collisions. The thermodynamic and kinetic conditions for the SHS reaction is discussed, and it shows that MA is a versatile method in inducing SHS reaction in systems with large heat of formation.

• Sponsoring Organization: USDOE
• OSTI ID: 247937
• Journal Information: Acta Materialia, Journal Name: Acta Materialia Journal Issue: 5 Vol. 44; ISSN XZ504Y; ISSN 1359-6454
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AGGLOMERATION
CARBON
CHEMICAL REACTION KINETICS
COMBUSTION
COMPOSITE MATERIALS
FORMATION HEAT
MARTENSITE
MELTING
MICROSTRUCTURE
MILLING
NICKEL
NICKEL ALLOYS
ORIENTATION
POWDERS
QUENCHING
TIME DEPENDENCE
TITANIUM
TITANIUM ALLOYS
TITANIUM CARBIDES
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION