The electron-metallography and crystallography of copper-aluminum martensites

Swann, P. R.; Warlimont, Hans

doi:10.1016/0001-6160(63)90086-5

Cited by 229 publications

(66 citation statements)

References 12 publications

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“…Such composite precipitates are also consistent with the results of Hasan et al [19,21] There are also light areas in Figure 6(c) away from the core of the globular particles. Swann and Warlimont [27] have shown Fig. 1(c).…”

Section: B Microstructure Examination By Temmentioning

confidence: 90%

The influence of friction stir processing parameters on microstructure of as-cast NiAl bronze

Oh-ishi

McNelley

2005

Metall Mater Trans A

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The influence of friction stir processing (FSP) parameters on the evolution of microstructure in an equilibrium-cooled, as-cast NiAl bronze (NAB) material was evaluated by optical microscopy (OM) and transmission electron microscopy (TEM) methods. A threaded pin tool was employed and tool rotation and traversing rates were varied in order to examine the spatial variation of stir zone microstructures in relation to FSP parameters. For processing at low rotation and traversing rates, the microstructure throughout the stir zone consists of elongated and banded grains of the primary ␣ and transformation products of the ␤ phase. Such microstructures reflect severe deformation at temperatures up to ϳ900°C in the ␣ ϩ ␤ two-phase region for this NAB material. Increasing rotation and traversing rates, coarse Widmanstätten ␣ near the surface in contact with the tool became apparent. The appearance of this constituent reflects nearly complete transformation to ␤ during FSP with peak temperatures of ϳ1000°C. Also, complex stir zone flow patterns, often referred to as onion ring structures, become distinct in the mid regions of the stir zones as rotation and traversing rates increase. Schematic representations illustrating the effect of FSP parameters on thermal cycles at various locations in stir zones were prepared based on microstructure observations. Thus, processing at higher rotation and traversing rates results in higher peak temperatures near the surface in contact with the tool but also in steeper temperature gradients when compared to lower rotation and traversing rates.

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Section: B Microstructure Examination By Temmentioning

confidence: 90%

The influence of friction stir processing parameters on microstructure of as-cast NiAl bronze

Oh-ishi

McNelley

2005

Metall Mater Trans A

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“…In the slipping, if it is performed by the migration of two extended half dislocations, then stacking faults will be formed between these two dislocations. In fact, the existence of the stacking faults recently been revealed in the martensite of Cu-Al alloy(18) (19).…”

Section: Discussionmentioning

confidence: 99%

Transmission Electron Microscope Observation of the Bainite of Carbon Steel

Shimizu

Nishiyama

1964

Trans. JIM

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The structure of the bainite in a 0.7% carbon steel has been studied by means of transmission electron microscopy and selected-area electron diffraction. The lower bainite consists of ferrite grains with internal fine cementite precipitates lying on one kind of planes (probably stacking fault planes). This behaviour of cementite is different from that of the tempered martensite, and moreover in the ferrite there are hardly seen any traces of the twin faults which are usually found in the martensite. On the other hand, in the upper bainite, the cementite plate is large and situated by the ferrite plate which contains a large number of dislocations. The electron diffraction patterns show that both the upper and lower bainites have nearly the same orientation relationships between the ferrite and the cementite. That is, Referring to these results and the habit of the precipitated cementite, the formation mechanism of the bainite is discussed in connection with the martensite transformation.

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“…It is well established that two types of thermally induced martensites, i.e., b 0 1 (18R, monoclinic) and c 0 1 (2H, orthorhombic), can form in the Cu-Al-Ni SMAs, depending on the Al content in the alloy. [31,32] It has been shown that a low Al content leads to the formation of b [31,32] Generally, Cu-Al-Ni alloys with approximately 12.5 to 13.5 wt pct Al were found to consist of both types of martensites. [31,32] Since, Cu-Al-Ni alloy strips contain approximately 13.5 wt pct Al (Table I) can be found to coexist in the present case.…”

Section: Figures 4(a) and (B)mentioning

confidence: 99%

“…[31,32] It has been shown that a low Al content leads to the formation of b [31,32] Generally, Cu-Al-Ni alloys with approximately 12.5 to 13.5 wt pct Al were found to consist of both types of martensites. [31,32] Since, Cu-Al-Ni alloy strips contain approximately 13.5 wt pct Al (Table I) can be found to coexist in the present case. Figure 11 also shows that the heat-treated strips consist of fully martensitic phase with two distinct types of morphologies, i.e., irregular zig-zag and parallel plate types.…”

Section: Figures 4(a) and (B)mentioning

confidence: 99%

Processing and Characterization of Cu-Al-Ni Shape Memory Alloy Strips Prepared from Prealloyed Powder by Hot Densification Rolling of Powder Preforms

Vajpai

Dube

Sangal

2011

Metall Mater Trans A

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The present work deals with the preparation of near-full density Cu-Al-Ni shape memory alloy (SMA) strips from argon-atomized prealloyed powder via a powder metallurgy (PM) route comprising cold die compaction to prepare powder preforms, sintering, and hot densification rolling of unsheathed sintered powder preforms under protective atmosphere at 1273 K (1000°C). It has been shown that argon-atomized spherical Cu-Al-Ni SMA powder consisted of very fine equiaxed grains and no appreciable grain growth occurred during sintering at 1273 K (1000°C). It also has been shown that no appreciable densification occurred during sintering, and densification was primarily achieved by hot rolling. The densification behavior of the sintered powder preforms during hot rolling was discussed. The hot-rolled Cu-Al-Ni strips were heat-treated at 1223 K (950°C) for 60 minutes and water quenched. The heat-treated strips consisted of equiaxed grains with average size approximately 90 lm. The heat-treated Cu-Al-Ni SMA strips consisted of self-accommodated b 0 1 martensite primarily, and showed smooth b 1 ) b 0 1 transformation behavior coupled with a very low hysteresis (%25 K (25°C)). The heattreated strips exhibited an extremely good combination of mechanical properties with fracture strength of 530 MPa and 12.3 pct fracture strain. The mode of fracture in the finished strip was primarily void-coalescence-type ductile together with some brittle transgranular type. The shape memory tests showed almost 100 pct one-way shape recovery after 100 bending-unconstrained heating cycles at 4 pct applied prestrain, exhibiting good stability of Cu-Al-Ni strips under thermomechanical actuation cycling. The two-way shape memory strain was found approximately 0.45 pct after 15 training cycles at 4 pct training strain.

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The electron-metallography and crystallography of copper-aluminum martensites

Cited by 229 publications

References 12 publications

The influence of friction stir processing parameters on microstructure of as-cast NiAl bronze

The influence of friction stir processing parameters on microstructure of as-cast NiAl bronze

Transmission Electron Microscope Observation of the Bainite of Carbon Steel

Processing and Characterization of Cu-Al-Ni Shape Memory Alloy Strips Prepared from Prealloyed Powder by Hot Densification Rolling of Powder Preforms

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