Volume Fraction Of Precipitated Phase Research Articles

Research on microstructure and properties of Cu-0.41%Cr-0.20%Zr alloy after solution-aging treatment

The phase analysis of Cu-0.41%Cr-0.20%Zr alloy treated by vacuum melting + solid solution + aging was carried out by means of SEM, TEM, EDXS and XRD. The results show that there are three phases in the alloy, namely the copper matrix phase, the chrome-rich phase and the zirconium-rich phase. The distribution of phase size is bimodal. The coarse phase size is microns scale, and the main components are elemental chromium and Cu5Zr, which are formed during the casting process and are not easy to dissolve in the subsequent aging process. The fine phase size is nanometer scale, and the composition is ordered bcc pure chromium and Cu5Zr. There is no chromium and zirconium intermediate phase. Under this condition, the volume fraction of precipitated phase is about 30 %. The heat treatment process can be further optimized by increasing the aging temperature, lengthening the aging time or adopting the second aging method.

Mechanism of internal magnetic energy of Cu-rich phase precipitation in Fe<sub>84</sub>Cu<sub>15</sub>Mn<sub>1</sub> alloy by phase field method

Based on the continuous phase field model, the precipitation behavior of Cu rich phase in Fe-Cu-Mn alloy under the action of internal magnetic energy is studied. The effects of internal magnetic energy on the average particle radius, volume fraction and Gibbs free energy of Cu rich phase at different temperatures and different Mn content and Cu content are investigated. The simulation results show that the lower the Mn content and the higher the Curie temperature, the greater the contribution of internal magnetic energy to free energy is, and the contribution of internal magnetic energy decreases with temperature increasing. The internal magnetic energy reduces the phase structure transition barrier and promotes the phase structure transition. The volume fraction of precipitated phase increases with Cu content increasing. Compared with the effect of internal magnetic energy on the volume fraction of precipitated phase, the effect of internal magnetic energy leads to a large volume fraction of precipitated phase. Therefore, under the action of internal magnetic energy, the Cu rich phase has larger average particle size, volume fraction and smaller coercivity. Finally, the change trend of alloy hardness is predicted.

Cold Rolling Deformation Characteristic of a Biomedical Beta Type Ti-25Nb-3Zr-2Sn-3Mo Alloy Plate and Its Influence on α Precipitated Phases and Room Temperature Mechanical Properties During Aging Treatment.

The microstructure characteristics and texture evolution of a biomedical metastable beta Ti–25Nb–3Zr–2Sn–3Mo (TLM; wt%) titanium alloy plate cold rolled at various reductions were studied in this article. <110> texture was easily formed in the TLM alloy plates, and a large number of dislocation tangles were generated in the β matrix in the process of cold rolling deformation. The dislocation lines, dislocation cells, subgrain boundaries, and other crystal defects introduced during cold rolling had a great impact on the morphological characteristics and volume fraction of precipitated phases during aging. These typical crystal defects could be considered as the major triggers of the formation of second phases, and they could also shorten the time of β→α phase transformation. α precipitated phases, with a size range of 150–500 nm, were formed within the β matrix in the cold deformed 34% in conjunction with the aging specimen, resulting in the relatively high tensile strength of 931 MPa and the acceptable elongation of 6.9%. When the TLM alloy plate was cold rolled at a reduction of 60% in conjunction with aging, the maximum value of ultimate strength (1,005 MPa) was achieved, but the elongation value was relatively low owing to the formation of α precipitated phases with a large size around the subgrain boundaries. In this paper, the influence of crystal defects and subgrain boundaries on the morphology characteristics and volume fraction of α precipitated phases and mechanical properties will be discussed in detail.

Borocarbide coarsening and the effect of borocarbide particle size on Charpy V-notch impact properties of medium-carbon boron-containing steel

Abstract Boron-added steel has been used in several automotive components in which the energy absorbed in impact testing is an important requirement. Previous thermodynamic studies have shown that boron addition promotes significant change in equilibrium phases, increasing the volume fraction of precipitated phases, mostly due to increased carbide stability and formation of borocarbides. As volume fraction, size and distribution of precipitates influence the absorbed energy in impact testing of steels, it is important to study M23(B,C)6 borocarbide precipitation and coarsening kinetics and its effects on Charpy V-notch absorbed energy of boron steels. In the present work, borocarbide coarsening kinetics were evaluated using optical microscopy in samples heat-treated at 880 0C for different times. The borocarbide coarsening kinetics data suggest that growth is controlled by an interfacial reaction mechanism. The Charpy V-notch absorbed energy decreases with increasing borocarbide section size and the embrittlement was successfully described by an empirical equation.

Borocarbide coarsening and the effect of borocarbide particle size on Charpy V-notch impact properties of medium-carbon boron-containing steel

Abstract Boron-added steel has been used in several automotive components in which the energy absorbed in impact testing is an important requirement. Previous thermodynamic studies have shown that boron addition promotes significant change in equilibrium phases, increasing the volume fraction of precipitated phases, mostly due to increased carbide stability and formation of borocarbides. As volume fraction, size and distribution of precipitates influence the absorbed energy in impact testing of steels, it is important to study M23(B,C)6 borocarbide precipitation and coarsening kinetics and its effects on Charpy V-notch absorbed energy of boron steels. In the present work, borocarbide coarsening kinetics were evaluated using optical microscopy in samples heat-treated at 880 0C for different times. The borocarbide coarsening kinetics data suggest that growth is controlled by an interfacial reaction mechanism. The Charpy V-notch absorbed energy decreases with increasing borocarbide section size and the embrittlement was successfully described by an empirical equation.

Adjust dilution level to suppress the precipitated phase by dilution level model of dissimilar metal laser welding with filler wire

To suppress the precipitated phase by adjusting the dilution level of 304 in the dissimilar metal (Hastelloy C-276/SUS 304) laser welding with filler wire, a mathematical model was established between laser parameters and the dilution level of 304 through energy conservation and mass conservation. And the model was verified by the corresponding experiment. The dilution level of 304 is linear with the single pulse energy E and inverse of wire feeding speed (1/VF), and it is also affected by energy melting efficiency and the ratio of two base metals melting. The dilution level of 304 is positively correlated with energy melting efficiency and negatively correlated with the ratio of two base metals melting. Defocusing distance and pulse width can affect dilution level of 304 by changing energy melting efficiency. Welding speed and laser beam offset can affect dilution level of 304 by changing the ratio of two base metals melting. At the same time, the influencing mechanism of the dilution level of 304 on the precipitated phase is revealed. The precipitated phase is directly related to the dilution level of 304. With the increase of dilution level of 304, the volume fraction of precipitated phase increases first and then decreases. When the dilution level of 304 is 24.0% ~ 35.2%, the volume fraction of precipitated phase is the biggest. And when the dilution level of 304 arrives to about 73.0%, the precipitated phase approximately disappears. As the result, the dilution level of 304 can be adjusted to suppress the precipitated phase by the dilution model in the laser welding Hastelloy C-276/SUS 304 with filler wire.

Microstructure evolution of DD6 during different heat treatment conditions

[001] oriented DD6 alloy was prepared by directional solidification in this experiment. γ′ phase precipitation phase structure of different morphology and size was obtained by different high temperature ageing heat treatment processes. Through this experiment, the feasibility of improving high temperature performance by adjusting the heat treatment process to change the microstructure of the single crystal was explored. The as-cast DD6 is first subjected to standard heat treatment(SHT). The single crystal sample after the standard heat treatment was further kept at 900 °C–1300 °C for 10 min, 30 min and 1 h, finally air-cooled respectively. Heat treatment process of DD6 was simulated using Jmatpro software. The individual phase transition temperatures of the alloy were determined by DSC experiments. And the size and volume fraction of precipitated phase of the alloy were estimated using Image-Pro Plus software. It is concluded that the microstructure of the alloy obtained after holding at 1100 °C for 30 min after standard heat treatment has the most uniform microstructure distribution.

Effect of Cooling Rate on Solidification Behavior and Microstructure Evolution of As-Cast Mg–5Al–2Ca–2Sm Alloy

In the present work, the Mg–5Al–2Ca–2Sm alloy was fabricated in stepped type sand mold, the cooling rate varied from 0.3 to 3.5 °C/s. The solidification behavior and microstructure evolution of Mg–5Al–2Ca–2Sm alloy were carried out by computer-aided cooling curve thermal analysis method, optical microscope (OM), X-ray diffraction analysis, scanning electric microscope and transmission electron microscope. The experimental results showed that the nucleation temperature of α-Mg phase decreased with increasing cooling rate. In addition, the grain size of α-Mg phase in Mg–5Al–2Ca–2Sm alloy were 95.47 ± 1.2 μm, 88.65 ± 1.5 μm, 71.24 ± 1.7 μm and 42.35 ± 1.3 μm, which were responds to the cooling rates of 0.3 °C/s, 0.5 °C/s, 1.2 °C/s and 3.5 °C/s, respectively. There were both Al2Sm (particle structures) and (Mg, Al)2Ca (lamella structure) phases in the Mg–5Al–2Ca–2Sm alloy under different cooling rates. However, there were Mg2Ca (blocky structure) in the samples cooled in 0.5 °C/s and 0.3 °C/s. The solidification sequence of precipitated phase in Mg–5Al–2Ca–2Sm alloy could be obtained as: Al2Sm → α-Mg → (Mg, Al)2Ca → Mg2Ca. Furthermore, the volume fraction of precipitated phase increased with the cooling rate. The volume fraction of precipitated phase in Mg–5Al–2Ca–2Sm alloy were 11.86 ± 0.7%, 13.05 ± 1.2%, 16.19 ± 0.8% and 20.77 ± 0.9%, which were responds to the cooling rates of 0.3 °C/s, 0.5 °C/s, 1.2 °C/s and 3.5 °C/s, respectively.

Effect of cooling rate and Al content on solidification behavior and microstructure evolution of as-cast Mg–Al–Ca–Sm alloys

In the present study, the Mg–xAl–2Ca–2Sm (x = 3, 5, 9 and 15) alloys were fabricated in sand mold with stepped type, and the cooling rates varied from 0.3 to 3.5 °C s−1. The solidification behavior and microstructure evolution of Mg–xAl–2Ca–2Sm alloys were carried out by computer-aided cooling curve thermal analysis method, optical microscope, scanning electron microscope, X-ray diffraction analysis and transmission electron microscope, respectively. The experimental results showed that the nucleation temperature and grain size of α-Mg phase decreased with increasing the cooling rate and Al content. However, the volume fraction of precipitated phase increases with cooling rate and Al content. In the Mg–3Al–2Ca–2Sm alloy cooled at 3.5 °C s−1, there were Al2Sm (rod and particle structures), Al11Sm3 (acicular structure) and (Mg, Al)2Ca (lamella structure) phases. But the Al11Sm3 phase and (Mg, Al)2Ca phase will gradually transform to the Al2Sm phase and Al2Ca phase, respectively. In addition, there were both Al2Sm (particle structures), Al2Ca (fish-bone structure) and β-Mg17Al12 (reticular structure) phases in Mg–15Al–2Ca–2Sm alloy cooled ranging from 3.5 to 0.3 °C s−1. In the Mg–xAl–2Ca–2Sm alloys, the Al2Sm phase mainly distribute in the grains, but all the Al11Sm3, (Mg, Al)2Ca, Al2Ca and β-Mg17Al12 phases distributed in the boundary of grains. The solidification sequence of precipitated phase in Mg–xAl–2Ca–2Sm alloys can be obtained: Al2Sm → α-Mg → Al2Ca → β-Mg17Al12.

Effect of Y on age hardening response and mechanical properties of Mg-xY–1.5LPC −0.4Zr alloys

Ageing hardening, microstructure and mechanical properties of Mg-xY–1.5LPC–0.4Zr (x=0, 2, 4, 6) alloys (LPC represents La-based rare earth metal) were investigated. It was found that the age hardening was enhanced, the grains became finer and the tensile strength was improved with the increase of Y content in Mg-Y–1.5LPC–0.4Zr alloy. The results show that the formed precipitates responsible for age hardening change from fine hexagonal-shaped equilibrium Mg12RE phase to metastable β′ phase with orthorhombic-bc crystal structure when Y is added into Mg-1.5LPC-0.4Zr alloy, and the volume fraction of precipitate phases also increases. The cubic-shaped β-Mg24Y5 precipitate phases were also observed at grain boundaries in Mg-6Y–1.5LPC–0.4Zr alloy. The distribution of prismatic shaped β′ phases and cubic shaped β-Mg24Y5 precipitate phases in Mg matrix may account for the remarkable enhancement of tensile strength of Mg-Y-LPC-Zr alloy. The Mg-6Y–1.5LPC–0.4Zr alloy exhibits maximum tensile strength at peak-aged hardness, and the values are 250 MPa at room temperature and 210 MPa at 250 °C.

Microstructure and mechanical properties of Mg- xY-1.5MM-0.4Zr alloys

Age hardening, microstructure and mechanical properties of Mg- xY-1.5MM-0.4Zr ( x=0, 2, 4, 6 wt.%) alloys (MM represents Ce-based misch-metal) were investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed that the formed precipitates being responsible for age hardening changed from fine hexagonal-shaped equilibrium Mg 12MM phase to metastable β′ phase with bco crystal structure when Y was added into Mg-1.5MM-0.4Zr alloy, and the volume fraction of precipitate phases also increased. With the increase of Y content in Mg-Y-1.5MM- 0.4Zr alloys, it was found that the age hardening was enhanced, the grain sizes became finer and the tensile strength was improved. The cubic-shaped β-Mg 24Y 5 precipitate phases were observed at grain boundaries in Mg-6Y-1.5MM-0.4Zr alloy. It was suggested that the distribution of prismatic shaped β′ phases and cubic shaped β-Mg 24Y 5 precipitate phases in Mg matrix might account for the remarkable enhancement of tensile strength of Mg-Y-MM-Zr alloy. It was shown that the Mg-6Y-1.5MM-0.4Zr alloy was with maximum tensile strength at aged-peak hardness, UTS of 280 MPa at room temperature and 223 MPa at 250°C, respectively.

Creep resistance of tin-based lead-free solder alloys

This paper reports on the microstructure-creep property relationship of three precipitation-strengthened tin (Sn)-based lead (Pb)-free solder alloys (Sn-0.7Cu, Sn-3.5Ag, and Sn-3.8Ag-0.7Cu) in bulk samples, together with Sn-37Pb as the alloy for comparison at temperatures of 303 K, 348 K, and 393 K. The creep resistance of these three Sn-based Pb-free solders increases, i.e., the steady-state creep rates decrease, with increasing volume fraction of precipitate phases for the Pb-free solder alloys. Their apparent stress exponents (na ∼ 7.3-17), which are all higher than that of pure Sn, attain higher values with increasing volume fraction of precipitate phases at constant temperature, and with decreasing temperature for the same solder alloy.

Morphology and mechanical properties of amine‐terminated butadiene‐acrylonitrile/epoxy blends

AbstractMorphology and mechanical properties of (amine terminated butadiene acrylonitrile rubber/diglycidyl ether of bis‐phenol‐A epoxy resin) blends of different compositions, cured in wide range of temperatures, are described. Curing at low temperature promoted formation of homogeneous materials with poor fracture resistance. On the contrary, at high temperature tough heterogeneous blends were obtained. Such blends showed phase inversion above 20 percent of rubber. The volume fraction of precipitated phase, determined on SEM micrographs, was higher than the amount of added rubber. A fracture mechanism to account for this is proposed. Extensive voiding and interface damage were observed in the low temperature cured materials. Such phenomena did not contribute to the fracture energy.