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The phase relations in the (1−x)Nd2Fe14B–xSm2Fe14B system over the whole concentration range have been studied by means of X-ray powder diffraction (XRD), differential thermal analysis (DTA) and scanning electron microscopy with energy-dispersive X-ray spectroscopy. Crystal structure parameters for all studied compositions of (Nd1−xSmx)2Fe14B have been determined by full-profile Rietveld refinements. These results revealed that all intermediate alloys of (Nd1−xSmx)2Fe14B are similar to the end member of the investigated system, Nd2Fe14B, with a tetragonal structure (space groupP42/mnm). The formation of continuous solid solutions has been found in this system. The normalized lattice parameters and unit-cell volumes of (Nd1−xSmx)2Fe14B solid solutions decrease linearly with increasing Sm content. The DTA measurements show that the melting temperature of (Nd1−xSmx)2Fe14B increases linearly with increasing Sm content and no metastable phases were detected. Based on the DTA data and XRD results, a tentative phase diagram for the pseudo-binary system Nd2Fe14B–Sm2Fe14B has been constructed.

The solid-state phase equilibria in the Fe–Ho–Pt ternary system at 1173 K (Ho ≤75%) were investigated by x-ray diffraction, scanning electron microscopy, and energy-dispersive x-ray spectroscopy techniques. The 1173 K isothermal section consists of 18 single-phase regions, 33 two-phase regions, and 16 three-phase regions. At 1173 K, we observed that the maximum solid solubility of Pt in Fe17Ho2, Fe23Ho6, Fe3Ho, and Fe2Ho is below 1 at.%. The binary phase Fe5Ho was not observed. The maximum solubility of Ho in α-Fe is about 1 at.%, and it is below 1.5 at.% in γ-(Fe, Pt), FePt, FePt3, and (Pt, Fe) (the solid solution of Fe in Pt). The existence of HoPt5, HoPt3, HoPt2, Ho3Pt4, HoPt, Ho5Pt4, Ho5Pt3, Ho2Pt, and Ho3Pt is confirmed, and the maximum solid solubility of Fe in them is below 1 at.%.

Large Na0.5K0.5NbO3 (NKN) piezoelectric single crystals were obtained by seed-free solid-state crystal growth method, which is a traditional sintering grain growth process, with LiBiO3 used as a sintering aid. The largest dimension of the single crystals obtained was 11 mm × 9 mm × 3 mm. In addition to the LiBiO3 doping content, temperature, and time effect of the crystal growth process was systematically investigated and considered from the kinetics point of view. With the assistance of Avrami analysis, parameters relevant to the crystal growth process were determined. Laue diffraction and transmission electron microscopy suggested an orthorhombic symmetry for the single crystalline structure. Dielectric-frequency-temperature measurements revealed an orthorhombic-tetragonal and tetragonal-cubic phase transition at 155°C and 405°C, respectively, both of which are typical of first-order transitions, and have a well-defined thermal hysteresis. Rayleigh analysis was performed regarding to the extrinsic reversible and nonreversible piezoelectric properties, and the result suggested a dominant intrinsic reversible piezoelectric contribution of 91.5% under E0 = 1 kV/cm AC amplitude. Such a single crystal growth process route is low cost and a relative simple preparation process.

The isothermal section of the Dy-Mn-As ternary system at 773 K has been investigated by using x-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. This isothermal section consists of 12 single-phase regions, 21 two-phase regions and 10 three-phase regions. The highest solid solubility of Dy in MnAs is about 0.65 at.%Dy, and that of Mn in DyAs is less than 0.79 at.%Mn. The maximum solubility of As in DyMn2 is less than 0.33 at.%As. No ternary compound was found to exist in this section at 773 K.

The solid-state phase equilibria in the ternary Fe-Pt-Tb system in the compositional region below 75 at.%Tb at 1173 K have been studied by using x-ray diffraction, scanning electron microscopy and energy dispersion spectroscopy techniques. The 1173 K isothermal section consists of 18 single-phase regions, 33 two-phase regions, and 16 three-phase regions. At 1173 K, the maximum solid solubility of Pt in α-(Fe, Tb) is less than 2 at.%Pt and that of Pt in Fe2Tb, Fe3Tb, Fe23Tb6, Fe17Tb2 is below 1 at.%Pt; the compounds Pt5Tb, Pt3Tb, Pt2Tb, Pt4Tb3, PtTb, Pt4Tb5, Pt3Tb5, PtTb2, and PtTb3 are confirmed to exist at 1173 K and the highest solid solubility of Fe in them is below 1 at.% Fe; the maximum solid solubility of Tb in α-(Fe, Pt), γ-(Fe, Pt), FePt, FePt3, and (Pt, Fe) (namely, the solid solution of Fe in Pt) is about 1, 2, 1.9, 1.5, and 1.5 at.%Tb, respectively. No ternary compound was found to exist in this section at 1173 K.

The structure and magnetostriction of the high-Pr content (Tb 0.2 Pr 0.8 ) (Fe 0.4 Co 0.6 ) 1.88− x C 0.05 B x (0 ≤ x ≤ 0.08) alloys homogenized at 700 °C for 7 days have been investigated by X-ray diffraction and magnetic measurement. It was found that the matrix of the (Tb 0.2 Pr 0.8 ) (Fe 0.4 Co 0.6 ) 1.88− x C 0.05 B x alloys belongs to (Tb, Pr) (Fe, Co, C, B) 2 phase with MgCu 2 -type structure. The Curie temperatures are derived from M–T curves, which showed a slight increase when 0 ≤ x ≤ 0.06, then decreases with further increasing x . The composition dependence of magnetostriction λ a (= λ ∥ − λ ⊥ ) for (Tb 0.2 Pr 0.8 ) (Fe 0.4 Co 0.6 ) 1.88− x C 0.05 B x alloys reaches a maximum value at x = 0.01 at room temperature. The double split (4 4 0) lines of the Laves phase overlap gradually with increasing x and finally approach to form a broadened peak for x = 0.03. The spontaneous magnetostriction λ 111 decreases with increasing boron contents.

The effects of Nd on the microstructure and magnetic properties of Nd x Co 50− x Pt 50 alloys ( x = 0, 0.5, 1.0, 1.5) were investigated. The XRD results indicated that all the alloys that were homogenized at 1000 °C mainly contain the A 1 (fcc) phase, while the alloys that were annealed at 675–750 °C consist of the hard magnetic face-centered-tetragonal (fct) phase and magnetically soft fcc phase. In any case, a few amount of NdPt 5 phase exists in alloys when x > 1.0. The (1 1 1) reflection belonging to fct phase shifts to a higher angle and the c/a ratio increases as the Nd content increases, which leads to the decrease in degree of ordering S . As a function of annealing time, both maximum values of the coercivity H c and remanence ratio m r were reached in Nd 0.5 Co 49.5 Pt 50 alloys annealed at 675 °C for 40 and 60 min, respectively. For the series of Nd x Co 50− x Pt 50 alloys annealed at 675 °C for 60 min, the H c decreases monotonically with the increase in Nd concentration but the value of m r is enhanced at first and then weakened, showing the highest value of 0.84 at x = 0.5.

The phase relationships in the Gd–Co–Al ternary system at 500°C have been investigated mainly by X-ray diffraction, scanning electron microscopy, and energy dispersion spectroscopy. The existence of two ternary compounds GdCo0.74Al1.26 and Gd2Co2Al has been confirmed. Twenty-two single-phase regions (including solid solution regions of the binary compounds), 43 two-phase regions, and 22 three-phase regions were found to exist at this isothermal section. In this work, no new binary or ternary phase was found.

The isothermal section of the Co–Pt–Nd system at 773 K was constructed in the whole concentration range by using X-ray diffraction, scanning electron microscopy, and energy dispersion spectroscopy techniques. Twenty-two single-phase regions (including solid solution regions of the binary compounds) were determined; 41 two-phase regions and 20 three-phase regions were identified to exist at this isothermal section. No new binary and ternary phases were found.

The isothermal section of the Pr–Pt–Co ternary system at 500 ∘ C has been determined in this study by X-ray diffraction, scanning electron microscopy and energy dispersion spectroscopy techniques. This isothermal cross-section consists of 20 single-phase regions (including solid solution regions of the binary compounds), 37 two-phase regions and 18 three-phase regions. The maximum solid solubility of Pt in Co 17 Pr 2 , Co 5 Pr, Co 19 Pr 5 ,Co 7 Pr 2 , Co 3 Pr,Co 2 Pr, Co 3 Pr 4 and CoPr 3 is less than 1 at.%Pt, and that of Co in PrPt, Pr 3 Pt 2 and Pr 7 Pt 3 below 1 at.%Co. The PrPt 5 phase dissolves up to 15 at.%Co and PrPt 2 up to 7.5 at.%Co. The highest solid solubility of Pr in α ( Co,Pt ) , e ( Co,Pt ) , α ( Co,Pt ) , CoPt 3 , CoPt and α ( Pt,Co ) is approximately 1.5 at.%Pr. No Co 2 Pr 5 phase and new ternary compounds were found.

The solid state phase equilibria in the Fe–Pt–Dy ternary system at 900 °C (Dy ≤ 75 at.%) were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersion spectroscopy (EDS) techniques. It is found that the 900 °C isothermal section consists of 18 single-phase regions, 33 two-phase regions and 16 three-phase regions. At 900 °C, it is observed that the maximum solid solubility of Pt in Fe 2 Dy and α-(Fe, Dy) is 5 at.% Pt and 3 at.% Pt, respectively. The binary phase Fe 5 Dy was not observed. The existence of DyPt 5 , DyPt 3 , DyPt 2 , Dy 3 Pt 4 , DyPt, Dy 5 Pt 4 , Dy 5 Pt 3 , Dy 2 Pt and Dy 3 Pt compounds is confirmed and the maximum solubility of Fe in them is below 1 at.% Fe; the maximum solubility of Dy in α-(Fe, Pt), γ-(Fe, Pt), FePt, FePt 3 and (Pt, Fe) (the solid solution of Fe in Pt) is 3 at.% Dy, 2 at.% Dy, 2 at.% Dy, 1.5 at.% Dy and 1.5 at.% Dy, respectively.

The solid-state phase equilibria in the Fe–Pt–Pr ternary system at 1173 K (Pr ≤ 70%) were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersion spectroscopy (EDS) techniques. The 1173 K isothermal section consists of 13 single-phase regions, 22 two-phase regions and 10 three-phase regions. At 1173 K, we have observed that the maximum solid solubility of Pt in α-Fe is below 1.5 at.% and the solid solution region of Pt in γ-Fe is from 2 to 35 at.%; the maximum solid solubility of Fe in Pt is 18 at.%. The maximum solubility of Fe in PrPt 5 , PrPt 3 , PrPt 2 , Pr 3 Pt 4 , PrPt, Pr 3 Pt 2 and Pr 7 Pt 3 is below 1 at.%. The maximum solubility of Pr in α-(Fe, Pt), γ-(Fe, Pt), FePt, FePt 3 and (Pt, Fe) (the solid solution of Fe in Pt) is 6, 2, 4, 4.5 and 1.5 at.%, respectively. In this work, it is found that the phase Pr 3 Pt 4 does not exist in the ternary system. The binary compounds Fe 7 Pr and Fe 2 Pr and any new ternary compounds were not observed.

Equilibrium phase diagrams for the ternary system Fe–Pt–Nd at 900 °C (Nd ≤ 70%) were established using X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersion spectroscopy (EDS) techniques. Thirteen single-phase regions (including solid solution regions of the binary compounds) were determined. Twenty-three two-phase regions and eleven three-phase regions were identified to exist at this isothermal section. The formation of the two previously reported binary phases, Fe 17 Nd 5 and Fe 2 Nd, could not be confirmed. Any new ternary compounds were not observed. In this work, it is found that the Nd 3 Pt 4 phase decomposes gradually into the two neighboring compounds βNdPt and NdPt 2 with introduction of Fe. For Fe contents higher than 5 at.%, the existence of Nd 3 Pt 4 phase was not observed in Fe–Pt–Nd ternary system.