Creep of a TiAl alloy: a comparison of indentation and tensile testing

Dorner, Dorothée; Röller, K.; Skrotzki, Birgit; Stöckhert, Bernhard; Eggeler, Gunther

doi:10.1016/s0921-5093(03)00205-3

Cited by 90 publications

(35 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Furthermore, impression creep avoids problems associated with localized stresses that characterize the tip region during indentation with sharp indenters. [17] The creep behavior of Mg alloys has been mainly studied by conventional tensile or compressive tests. In a few cases, however, localized creep test methods have been used to evaluate the creep behavior of different magnesium alloys.…”

Section: Introductionmentioning

confidence: 99%

Effects of Rare Earth Element Additions on the Impression Creep Behavior of AZ91 Magnesium Alloy

Kabirian

Mahmudi

2009

Metall Mater Trans A

View full text Add to dashboard Cite

The effects of 1, 2, and 3 wt pct rare earth (RE) element additions on the microstructure and creep behavior of cast AZ91 Mg alloy were investigated by impression tests. The tests were carried out under constant punching stress in the range 200 to 650 MPa at temperatures in the range 425 to 525 K. Analysis of the data showed that for all loads and temperatures, the AZ91-2RE alloy had the lowest creep rates and, thus, the highest creep resistance among all materials tested. This is attributed to the formation of Al 11 RE 3 with a branched morphology, reduction in the volume fraction of the eutectic b-Mg 17 Al 12 phase, and solid solution hardening effects of Al in the Mg matrix. The stress exponents and activation energies were the same for all alloy systems studied, 5.3 to 6.5 and 90 to 120 kJ mol À1 , respectively, with the exception that the activation energy for the AZ91-3RE system was 102 to 126 kJ mol À1 . An observed decreasing trend of creep-activation energy with stress suggests that two parallel mechanisms of lattice and pipe diffusion-controlled dislocation climb are competing. Dislocation climb controlled by dislocation pipe diffusion is controlling at high stresses, whereas climb of edge dislocations is the controlling mechanism at low stresses.

show abstract

Section: Introductionmentioning

confidence: 99%

Effects of Rare Earth Element Additions on the Impression Creep Behavior of AZ91 Magnesium Alloy

Kabirian

Mahmudi

2009

Metall Mater Trans A

View full text Add to dashboard Cite

show abstract

“…5 In such cases, the material resistance to creep deformation is of great concern due mainly to the fact that the stress and strain concentrations at the solder joints must be effectively relaxed by creep to guarantee solder joint reliability. 15,16 It is therefore the aim of this paper to study the creep behavior of the Sn-9Zn-0.5Ag and Sn-9Zn-0.5Al alloys, compared with that of the eutectic Sn-9Zn alloy. This has been achieved using the impression creep testing technique, which has been widely used in the creep study of various solder materials.…”

Section: Introductionmentioning

confidence: 99%

Effects of Ag and Al Additions on the Structure and Creep Properties of Sn-9Zn Solder Alloy

Mahmudi

Geranmayeh

Noori

et al. 2008

Journal of Elec Materi

View full text Add to dashboard Cite

Creep behavior of the eutectic Sn-9Zn, Sn-9Zn-0.5Ag, and Sn-9Zn-0.5Al solder alloys was studied by impression testing under constant punching stress in the range of 60 MPa to 130 MPa and at temperatures in the range of 298 K to 370 K. Analysis of the data showed that, for all loads and temperatures, Sn-9Zn-0.5Al had the lowest creep rates and thus the highest creep resistance among all materials tested. The creep resistance of Sn-9Zn-0.5Ag was slightly lower than that of the Al-containing alloy. The enhanced creep behaviors of the ternary alloys are attributed to the presence of AgZn 3 and very fine Zn particles, which act as the main strengthening agents in the Sn-9Zn-0.5Ag and Sn-9Zn-0.5Al alloys, respectively. Assuming a power-law relationship between the impression rate and stress, average stress exponents of 6.9, 7.1, and 7.2 and activation energies of 42.1 kJ mol -1 , 42.9 kJ mol -1 , and 43.0 kJ mol -1 were obtained for Sn-9Zn, Sn-9Zn-0.5Ag and Sn-9Zn-0.5Al, respectively. These activation energies are close to 46 kJ mol -1 for dislocation climb, assisted by vacancy diffusion through dislocation cores in the Sn. This, together with the stress exponents of about 7, suggests that the operative creep mechanism is dislocation climb controlled by dislocation pipe diffusion.

show abstract

“…12,13 Since the creep behavior of solders is strongly microstructure dependent, a significant body of the recent work on solder creep has been based on actual solder balls attached to packaging substrates, e.g., via impression creep. [14][15][16][17][18] In this test, a slightly flattened solder bump is loaded with a flat-tipped cylindrical indenter, producing a creep curve that is very similar to a compression creep curve. The test allows establishment of steady-state behavior within just a few hours, and enables testing of individual solder balls attached to microelectronic substrates.…”

Section: Introductionmentioning

confidence: 99%

Effect of Ag and Cu Concentrations on the Creep Behavior of Sn-Based Solders

Chen

Dutta

2007

Journal of Elec Materi

View full text Add to dashboard Cite

The creep behavior of Sn-1Ag-0.5Cu, Sn-2.5Ag-1Cu and Sn-4Ag-0.5Cu ball grid array (BGA) solder balls and 99.99% pure polycrystalline bulk Sn was studied using impression creep and related to the microstructure. Sn-Ag-Cu solders generally consist of primary dendrites/grains of b-Sn, and a eutectic microconstituent comprising fine Ag 3 Sn and Cu 6 Sn 5 particles in b phase. With increasing concentrations of Ag and Cu in the alloy, the proportion of the eutectic microconstituent in relation to the primary b phase increases. In pure Sn and Sn-1Ag-0.5Cu, the b grains form the continuous matrix, whereas in Sn-2.5Ag-1Cu and Sn-4Ag-0.5Cu, the eutectic microconstituent forms a continuous network around the b grains, which form isolated islands within the eutectic. The steady-state creep behavior of the alloys was dominated by the response of the continuous microstructural constituent (b-Sn or solid solution b for pure Sn and Sn-1Ag-0.5Cu, and the eutectic microconstituent for Sn-2.5Ag-0.5Cu and Sn-4Ag-0.5Cu). In general, the steady-state creep rate decreased with increasing alloy content, and in particular, the volume fraction of Ag 3 Sn and Cu 6 Sn 5 precipitates. The rate-limiting creep mechanism in all the materials investigated here was core diffusion controlled dislocation climb. However, subtle changes in the stress exponent n and activation energy Q were observed. Pure Sn shows n = 5, Q = 42 kJ/mol, Sn-1Ag-0.5Cu shows n = 5, Q = 61 kJ/mol, whereas both Sn-2.5Ag-1Cu and Sn-4Ag-0.5Cu show n = 6 and Q = 61 kJ/mol. Rationalizations for the observed changes of n and Q are provided, based on the influence of the microstructure and the solute concentrations.

show abstract

Creep of a TiAl alloy: a comparison of indentation and tensile testing

Cited by 90 publications

References 19 publications

Effects of Rare Earth Element Additions on the Impression Creep Behavior of AZ91 Magnesium Alloy

Effects of Rare Earth Element Additions on the Impression Creep Behavior of AZ91 Magnesium Alloy

Effects of Ag and Al Additions on the Structure and Creep Properties of Sn-9Zn Solder Alloy

Effect of Ag and Cu Concentrations on the Creep Behavior of Sn-Based Solders

Contact Info

Product

Resources

About