Ll{sub 2} Al{sub 3} Ti-based alloys with Al{sub 2}Ti precipitates; II: Deformation behavior of single crystals

Journal Article · Tue Feb 01 04:00:00 EST 1994 · Acta Metallurgica et Materialia

DOI:https://doi.org/10.1016/0956-7151(94)90506-1· OSTI ID:143152

Wu, Z L; Pope, D P ^[1]

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1. Univ. of Pennsylvania, Philadelphia, PA (United States). Dept. of Materials Science and Engineering

The operating slip systems and flow behavior of single crystalline Al{sub 66.8}Ti{sub 27.4}Fe{sub 5.8}, a two phase Ll{sub 2}+Al{sub 2}Ti materials, was investigated as a function of temperatures using specimens with compressive axes near [001], [{bar 1}3], [{bar 1}2], [{bar 1}33]. The materials shows a very limited compressive ductility, and fracture occurs by cleavage along planes of low indices, such as (011), (001), (013) and (111). Slip occurs exclusively on the octahedral slip systems at low temperatures, and on both octahedral and cube systems at high temperatures. A transition in operating slip systems from octahedral slip to cube slip, similar to the one seen in Ni{sub 3}Al-type alloys, occurs as the temperature increases and as the orientation of the specimens change from near-[001] to near-[{bar 1}11]. The transition in slip system is attributed to the hardening effect of the Al{sub 2}Ti precipitates, rather than to the anisotropy of APB energy on cube and octahedral slip planes of the matrix. Because of the large hardening effect of the Al{sub 2}Ti, the two phase material is substantially stronger than single Ll{sub 2} phase materials. The shape (but not the level) of the flow stress-temperature curve for the two phase material resembles that of the single phase Ll{sub 2} material at low and intermediate temperatures. At high temperatures, however, the flow stress of the two phase material exhibits a sharp decrease, a feature which is not observed in the single phase Ll{sub 2} materials and can be correlated with a continuous dissolution of the Al{sub 2}Ti precipitates at high temperatures.

• OSTI ID: 143152
• Journal Information: Acta Metallurgica et Materialia, Journal Name: Acta Metallurgica et Materialia Journal Issue: 2 Vol. 42; ISSN 0956-7151; ISSN AMATEB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM BASE ALLOYS
DEFORMATION
FRACTURE PROPERTIES
IRON ALLOYS
PHASE TRANSFORMATIONS
TITANIUM ALLOYS
TRANSITION TEMPERATURE