Search results

The distribution of d¢ phase distribute more homogeneously in the grains.
The properties of Al-Cu-Li alloys are determined by the structure, including the macrostructure, such as texture and grain shape, as well as microstructure, such as the type, size, number and distribution of precipitates within the grains and at the grain boundaries[7,8].
Electron back scattering diffraction technique was applied to investigate the grain size, grain shape and misorientation angle distribution using JEM-7001F.
With the increase of compression deformation, the number of the precipitats increase firstly and then decrease, and the size of precipitates increase gradually.
The influence of grain structure on the ductility of the Al-Cu-Li-Mn-Cd alloy 2020.

It shows how grain sizes change after irradiation Experimental data suggests that non-irradiated sample of 08Cr18Ni10Ti is similar to post austenized and aged material: polyhedral grains with few inclusions of secondary phases (about 1) in a lattice and at grain boundaries (see Fig.3).
Certain grains demonstrate twinning layers.
Irradiated samples have tendency to increased secondary grains.
In Fig. 1, it is observable that with increase in irradiation dose, the number of fine grained inclusions grows (1 micrometer).
Secondary inclusions are supposedly fine-grained carbides of M23C6 type.

The SRM propellant grain is HTPB composite propellant, Assuming that grains as an isotropic linear viscoelastic material, the thermal stress and thermal strain of grain does not considered.
One coupling step contains some sub-iterations, in order to solve the field equation, each solver will obtain the required data from another solver in every coupling sub-iteration. sub-iteration will stop when it reach to a given maximum iteration number or all physical fields converge at this coupling step, then calculation will switch to the next coupling step, ensuring each coupling calculation is implicit.
The front surface of the propellant grain locates in x = 0.022, and the back grain surface locates in x = 0.347.
(2) The cold-flow gas pressure has a great impact on the grain in a short time, especially in head end of the grain
(3) Grains deformation is mainly concentrated on point A and point C, and gradually increases with time; stress is mainly concentrated on the joint of grain front surface and the motor case, the stress concentration generated here may cause grain offsticky

The former has the grain size of 80 mesh, and Table 1 shows its composition; The grain size of the latter one is less than 50 nm,and it is prepared by Hefei Kaier Nano-meter Energy& TechnologyCo.
When the addition of nano TiN is 1%, the nano TiN play a role of nucleating agentto promote formation of large numbers of close grains.
When the addition amount of TiN is 1%, wear weightlessness is 0.1177 mg,reducing by 5.40% than sample of number 0, this is related to that M7C3 separate out as hupereutectic overeutectic carbide precipitation phase.
M7C3 has superior hardness of 672.89 HV and appear in the form of homogeneous grains.
(2)When the addition amount of TiN is 1%, the grain is refined obviously, the wear weightlessness is 0.1177 mg,which means the best wear resistance.

Introduction Severe plastic deformation (SPD) methods are an effective means of obtaining nano- and ultrafine-grained structures for various metals and alloys. [1-5] A large number of works is devoted to the study of processing features of metallic materials by such methods, including the processes of structural-phase transformations.
As a result of heat treatment, a coarse-grained structural state was formed in both materials.
The studied samples of commercially pure M1 copper and Cu-1.1Cr alloy in the initial state had a coarse-grained structure (Fig. 2) with an average grain size of 60 ± 6 and 120 ± 9 μm, respectively.
Mechanical properties and energy dissipation in ultrafine-grained AMts and V95 aluminum alloys during dynamic compression.
High-strain-rate response of ultra-fine-grained copper.

Table 2 The specimen number of alloy at different heat treatment Specimen number Heat treatment A1 Hot Forging A2 Solution treated at 900oC A3 Aged at 400oC for 2h A4 Aged at 450oC for 2h A5 Aged at 500oC for 2h A6 Aged at 550oC for 2h For microstructural observation, the samples were gradually ground with abrasive paper from 200# to 5000# and then the samples were polished and etched in etchant of 2g FeCl3 +2ml HCl+98ml water to test the change in organization of grain size and shape.
The grains did not significantly change with increasing aging temperature.
On the contrary, the grain coarsening caused the decrease of the yield strength.
However there shows a growth in the number of dimples.
Wang, Grain growth kinetics of a fine-grained AZ31 magnesium alloy produced by hot rolling, J.

Substructure analysis of state A1 and I1 show, that a relatively large number of irregular, rod-shaped and oval carbide particles, often arranged in clusters, were precipitated at the primary original austenite grain boundaries.
A relatively large number of rod-shaped and oval shaped particles were found at the interface of the tempered martensite and bainite mainly in the form of clusters and also inside the tempered bainite with higher particle distribution.
These precipitates are most probably carbides that precipitated also at the original austenite grain boundaries during tempering.
Fig. 7 Particles present on original austenitic grain boundaries (I1), carbon extraction replicas, TEM.
Fig. 8 Detail of the cluster of particles present on original austenitic grain boundaries (I1), carbon extraction replicas, TEM.

The hydrogen gas evolution from the specimen was evaluated from the hydrogen ion current, where the mass number M/e=2 was selected.
Table 2 Manufacturing condition and the grain size of the plate specimens.
In addition, under the same alloy group, the specimens with relatively finer grains (B and D) showed higher fracture strain than that with coarse grains (A and C).
By comparing the hydrogen evolution results and the fracture morphology between Fig.2 and Fig.3, it is presumed that a number of hydrogen atoms are trapped at the GBs before fracturing.
However, the arrangement of Ag particles on GBs was not observed in all the grain boundaries.

Their experimental results showed an increase in alignment of SiC particles in the direction of extrusion, reduction in number of SiC particulate clusters, and improved distribution of the SiC particles as the extrusion temperature decreased.
Average grain sizes of 10-20 μm were achieved by this two-step process.
Grain size refinement.
Fig.8 Grain size of billet and extruded tube Tensile test.
A grain size of less than 10 μm for the extruded products with extrusion temperature of 300℃ was obtained, which is much smaller than 84 μm for the grain size of the billets.

The modification has obvious refining effect on primary silicon and eutectic silicon grains, electromagnetic stirring has refining effect on primary silicon grains, and eutectic silicon grains appear coarsening phenomenon.
Thus, eutectic silicon grains change from coarse needle flake to fine dot shape.
It can be seen from the figure that with the increase of the constant temperature time, the primary silicon grains in the aluminum silicon alloy increase and the number decreases.
Electromagnetic stirring can refine and passivate the primary silicon grains, but coarsen the eutectic silicon grains.
Räbiger, et al., Grain size control in Al–Si alloys by grain refinement and electromagnetic stirring, J.