Ductility improvement in high strength Ti-Mo allovs by transition of deformation mode

Experiments at temperatures from 20 C to 400 C at two strain rates (.0001/s and .000005/s) establish that: (1) at room temperatures, binary and microalloyed ( 1000 ppm La, Y, Mo, Ti) NiAl shows negligible ductility, independent of grain size over the range 5 to 140 micrometers; (2) at 295 C the tensile elongation of binary 51 Ni/49 Al increases from 1% to about 5% upon decreasing the grain size to below approximately 10 micrometers; (3) similarly, at 400 C the ductility increases from about 2% to 15% upon decreasing the grain size to below 15 micrometers; (4) the ductility of fine grained (7 micrometer) binary aggregates deformed at 295 C increases from approximately 5% to 12% upon decreasing the strain rate from .0001/s to .000005/s; (5) partial recrystallization (10% to 20%) of warm extruded binary and microalloyed material imparts 1% to 2% ductility at room temperature where fully recrystallized material is brittle; (6) the yield strength obeys a Hall-Petch relationship; and (7) when ductility is not observed, fracture coincides with yielding. The mechanisms underlying the flow and fracture of NiAl are discussed in terms of the nucleation and growth of microcracks. The concept of a critical grain size is considered in the light of the results.

Ductility (Earth science)

Brittleness

Recrystallization (geology)

Elongation

Source

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Citations (1)

Study on Mechanical Property of Ti-6Al-4V Alloy Bar by Huge-deformation Hot Rolling

Rejiagong gongyi (2009)

Yongqing Zhao

The new type of Ti-6Al-V alloy was obtained using huge-deformation hot rolling. The tensile and impact properties of Ti-6Al-4V alloy bar and non-huge-deformation bar were measured. The fracture morphology of alloy bar was observed. The results show that the bar's tensile strength changes little. Compared with non-huge-deformation, the elongation increases by 30%, impact ductility increases by 20%. Although the refined microstructure can not make the tensile strength increase sharply, the ductility increases. The observation of tensile and impact fracture shows that the fracture is flat, the dimple is shallow, the hole is little. But its elongation and impact ductility are higher than those of non-huge deformation bar. This phenomenon is irregular.

Dimple

Ductility (Earth science)

Elongation

Bar (unit)

Deformation mechanism

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Citations (0)

Strong and ductile beta Ti–18Zr–13Mo alloy with multimodal twinning

Materials Research Letters (2019)

Jinyong Zhang Fan Sun Zheng Chen Yang Yang Baolong Shen

Body-centred cubic (BCC) Ti–18Zr–13Mo (wt%) alloy displays excellent yield strength (≈800 MPa), stable hardening (rate > 1500 MPa) and uniform ductility >18%, resulting from multi-TWIP (multiple twinning-induced plasticity) strengthening effect. This multimodal mechanisms include micro-scale {332}<113> deformation twinning (DT), nano-scale {112}<111> DT and a rare {5 8 11}<135> DT mode. Martensitic phase transformation is completely suppressed and the sample stays a single-phase solid solution throughout the deformation. In situ electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) were used to characterize the multi-TWIP and dynamic Hall–Patch effect, with dislocation slip and large grain distortions at twin interfaces.

10.1080/21663831.2019.1595763

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Citations (86)

Correlation of tensile properties, deformation modes, and phase stability in commercial β-phase titanium alloys

Metallurgical Transactions A (1987)

Shuji Hanada Osamu Izumi

Titanium alloy

10.1007/bf02825707

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Citations (178)

Dislocation hardening and phase transformation-induced high ductility in Ti-6Al-4V with a heterogeneous martensitic microstructure under tensile load

Journal of Alloys and Compounds (2021)