The influence of post quench ageing in the beta-phase on the transformation characteristics and the physical and mechanical properties of martensite in a Cu-Al-Ni shape memory alloys.

Humbeeck, Jan Van; Chandrasekaran, M.; Delaey, L.

doi:10.2355/isijinternational.29.388

Cited by 41 publications

(21 citation statements)

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“…Many discussions have already been focused on the origin of the transformation temperature increase [2][3][4][5][6] and the present results clearly show that the main modifications are not induced by the 72 precipitation. On the other hand, the sharp rise of As and Ms, similarly observed in the two samples, could be ascribed to the recovery of the second neighbouring order in the austenite phase [6][7].…”

Section: Discussionsupporting

confidence: 55%

“…The resistivity fall being smaller in this sample could indicate that the vacancies are either less numerous either less mobile than in the polycrystal. In any case, this kind of result shows that the vacancy migration process plays a crucial role in the austenite reordering [6][7][8]. Moreover, the scarce austenite ordered domains being localised at the older martensite/martensite interfaces indicate that these interfaces are preferential zones for the quenched vacancy coalescence.…”

Section: Discussionmentioning

confidence: 72%

“…On the other hand, the sharp rise of As and Ms, similarly observed in the two samples, could be ascribed to the recovery of the second neighbouring order in the austenite phase [6][7].…”

Section: Discussionmentioning

confidence: 87%

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TEM study of the austenitic phase of high Ms CuAlNi alloys

et al. 2001

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Abstract. CuAINi shape memory alloys, with Ms close to 130 °C (in the as-quenched state) have been studied on single crystalline and polycrystalline samples. The specimens have been quenched after heat treatment at 850 °C. The structural study discussed in the present paper has been performed using electrical resistivity and TEM (Transmission Electron Microscopy) analysis. The electron diffraction patterns show that the austenite of the two as-quenched samples is a disordered and body-centred cubic structure. Then, after one annealing at 165 °C performed in the TEM, the polycrystalline austenite reorders in a facecentred cubic structure (L2 r type), while the single crystalline austenite (annealed at 172 °C) stays in the disordered state. Nevertheless, during the heating of the single crystal sample above Ap, ordered precipitates appear in the parent phase along the former martensite-martensite interface traces. In addition, precipitates of the Cu 9 AL, (y 2 ) phase are evidenced in the two samples after annealings below 172 °C. These observations, the structural difference between the single-and the polycrystalline austenite and the low temperature precipitation of the Y2 phase, are quite original and have to be discussed by taking into consideration previous investigations performed on similar alloys.

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Section: Discussionsupporting

confidence: 55%

Section: Discussionmentioning

confidence: 72%

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TEM study of the austenitic phase of high Ms CuAlNi alloys

et al. 2001

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“…From the described results, the ageing stages can be interpreted as follows: recovery of second neighbors order suppressed during the quench causes temperature increase in the first stage [7], while precipitation of second phase particles is responsible for the latter srages of ageing [5,7,8]. A former decrease of transformation temperatures observed by several authors upon ageing Cu-Al-Ni alloys [7,8], which they attributed to first neighbor reorder, has not been observed in the present alloys.…”

Section: Ln Ageing Time (S) Ln Ageing Time (S)mentioning

confidence: 63%

Effect of Mn on Ageing of Cu-Al-Ni-Mn-B Alloys

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Cesari

1995

J. Phys. IV France

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“…Performance and properties of materials exhibiting a thermoelastic martensitic transformation (TMT) are closely related to the stability of their defect structure [1,2]. From the engineering standpoint, the properties of TMT materials under the ultimate conditions of high-energy impact loading are of a great importance.…”

Section: Introductionmentioning

confidence: 99%

Transformation temperatures, elastic and anelastic properties of Cu-Al-Ni crystals subjected to impact loading

et al. 2001

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Experimental investigations of the influence of impact loading on properties of Cu-AI-Ni single crystals have been performed. Crystals in the p\ phase were impacted with pulses of a uniaxial plane strain wave with a duration of about 2X10" 6 s. A normal component of stress in the direction of the pulse propagation ranged from 0.5 to 5.4 GPa. For as-quenched and impacted crystals martensitic transformation temperatures were determined, the Young's modulus (YM), strain amplitudeindependent and strain amplitude-dependent internal friction were measured at a frequency of about 100 kHz over the temperature range of 300-90 K for strain amplitudes of IO" 7 -2xlO" 4 . Experimental results indicate that Pi->Yi' martensitic transformation (MT) and plastic deformation of the martensite are induced by the impact. The impact loading generates a «structure memory effect»: the YM in the austenite is not sensitive to the impact, but the consequent temperature-induced MT reveals a dramatic influence of the impact on the YM of the y,' martensite. The conclusion is drawn that the observed effect is fundamentally similar to the two-way memory effect, but is extremely sensitive to the impact stress. The origin of this phenomenon is attributed to the internal stresses, created by impact, which control the nucleation of preferentially oriented anisotropic martensitic variants during temperature-induced MT in impacted crystals. No influence of the impact loading on the transformation temperatures was detected for pi->Yi' MT, in contrast to elastic properties of the martensitic phase, indicating that structural changes due to the high-velocity impact do not affect appreciably the thermoelastic equilibrium and hysteretic motion of parent -martensite boundaries during the MT.

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The influence of post quench ageing in the beta-phase on the transformation characteristics and the physical and mechanical properties of martensite in a Cu-Al-Ni shape memory alloys.

Cited by 41 publications

References 0 publications

TEM study of the austenitic phase of high Ms CuAlNi alloys

TEM study of the austenitic phase of high Ms CuAlNi alloys

Effect of Mn on Ageing of Cu-Al-Ni-Mn-B Alloys

Transformation temperatures, elastic and anelastic properties of Cu-Al-Ni crystals subjected to impact loading

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