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Fig. 3 XRD patterns of (a) A356/TiB2 MMCs and (b) extracted TiB particles from A356-10 wt.% TiB, composite (Ref 18)

Figure 3 XRD patterns of (a) A356/TiB2 MMCs and (b) extracted TiB particles from A356-10 wt.% TiB, composite (Ref 18)

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Table 1 Properties of different reinforcements that can be prepared in situ (Ref 14-16) refiners. The synthesis of Al-TiB2 composite using K,TiF, and KBF, salt reaction in molten Al was patented by London and Scandinavian Metallurgical Co. Ltd. in 1993 (Ref 17). Many researchers have since synthesized in situ TiB»-reinforced composites via K,TiF, and KBF, salt reaction in Al alloys (Ref 17-23). The TiB, particles formed in situ in the Al melt by this method are a few microns in size (Ref 11-13, 18, 20, 24-30). A number of researches have reported the presence of Al;Ti phase in Al-TiB, composites, which is found to degrade the overall mechanical properties of the composite (Ref 31, 32). Later, it was found that AI,Ti formation can be suppressed by increasing the reaction time and temperature and properly controlling the proportion of salts (Ref 8, 18, 24, 25, 33-37). A schematic diagram of synthesis of A356-TiB, composites by this method is shown in Fig. 2.
Table 1 Properties of different reinforcements that can be prepared in situ (Ref 14-16) refiners. The synthesis of Al-TiB2 composite using K,TiF, and KBF, salt reaction in molten Al was patented by London and Scandinavian Metallurgical Co. Ltd. in 1993 (Ref 17). Many researchers have since synthesized in situ TiB»-reinforced composites via K,TiF, and KBF, salt reaction in Al alloys (Ref 17-23). The TiB, particles formed in situ in the Al melt by this method are a few microns in size (Ref 11-13, 18, 20, 24-30). A number of researches have reported the presence of Al;Ti phase in Al-TiB, composites, which is found to degrade the overall mechanical properties of the composite (Ref 31, 32). Later, it was found that AI,Ti formation can be suppressed by increasing the reaction time and temperature and properly controlling the proportion of salts (Ref 8, 18, 24, 25, 33-37). A schematic diagram of synthesis of A356-TiB, composites by this method is shown in Fig. 2.
Fig. 1 Number of papers on (a) Al-based cast in situ composites and (b) Various reinforcements
Fig. 1 Number of papers on (a) Al-based cast in situ composites and (b) Various reinforcements
Fig. 2. Schematic diagram for the synthesis of A356-TiB2 compos- ites (Ref 18) extracted particles from the composite as shown in Fig. 3. They reported that a melt temperature of 800 °C and reaction time of | h with stirring at an interval of 10 min were opti- mum for synthesis of these composites without any Al,Ti for- mation. They also showed that the TiB, particles act as
Fig. 2. Schematic diagram for the synthesis of A356-TiB2 compos- ites (Ref 18) extracted particles from the composite as shown in Fig. 3. They reported that a melt temperature of 800 °C and reaction time of | h with stirring at an interval of 10 min were opti- mum for synthesis of these composites without any Al,Ti for- mation. They also showed that the TiB, particles act as
Fig. 4 (a) Variation of excess free energy with temperature for TiAl;, TiB2 and AJB» and (b) standard free energy for possible reactions (Ref 38) (a) Al+ 2B — AIBz, (b) ALTi + 2Ti > 3TiAl, (c) 3Al + Ti — ALTi, (d) ALTi + 2B > TiB, + 3Al and (e)Ti + 2B — TiB, (Ref 39)
Fig. 4 (a) Variation of excess free energy with temperature for TiAl;, TiB2 and AJB» and (b) standard free energy for possible reactions (Ref 38) (a) Al+ 2B — AIBz, (b) ALTi + 2Ti > 3TiAl, (c) 3Al + Ti — ALTi, (d) ALTi + 2B > TiB, + 3Al and (e)Ti + 2B — TiB, (Ref 39)
Fig. 5 Microstructure of Al-7Si alloy with (a) 0, (b) 5, and (c)10 wt.% TiB, particles and the higher magnification insets in (a) and (c) show the difference in Si particle size and shape (Ref 11)
Fig. 5 Microstructure of Al-7Si alloy with (a) 0, (b) 5, and (c)10 wt.% TiB, particles and the higher magnification insets in (a) and (c) show the difference in Si particle size and shape (Ref 11)
Fig. 6 Hardness of the composites as a function of aging time for A356 and Al-4Cu alloy reinforced TiB, composite (Ref 18, 43
Fig. 6 Hardness of the composites as a function of aging time for A356 and Al-4Cu alloy reinforced TiB, composite (Ref 18, 43
Fig. 7 (a) Specific wear rate of Al-7Si alloy-based composites as a function of load and hardness and (b) average value of Fe content on worn surface measured from EDS as a function of amount of TiB2 and applied load (Ref 20) more Fe removal from the disk and results in an increase in percentage of Fe in the wear surface with increase in TiB, and normal load as shown in Fig. 7. The SEM micrographs of worn surface of Al-7Si alloy and AlI-7Si-10TiB, composite are shown in Fig. 8. It was observed that Al-7Si alloy on sliding at high load deforms plastically and progressive transfer of material to the counterface, and its re-depostition leads to seizure of matrix Al-7Si alloy. In case of Al-7Si alloy, the wear Kumar et al. (Ref 20) have studied the wear property of Al- 7Si alloy reinforced with 5 and 10 wt.% TiB» composite and found 36 and 66% improvement in wear properties, respec- tively, compared with the Al-7Si alloy. The wear rate reduced with increase in wt.% TiB>. Also the increase in TiB> causes
Fig. 7 (a) Specific wear rate of Al-7Si alloy-based composites as a function of load and hardness and (b) average value of Fe content on worn surface measured from EDS as a function of amount of TiB2 and applied load (Ref 20) more Fe removal from the disk and results in an increase in percentage of Fe in the wear surface with increase in TiB, and normal load as shown in Fig. 7. The SEM micrographs of worn surface of Al-7Si alloy and AlI-7Si-10TiB, composite are shown in Fig. 8. It was observed that Al-7Si alloy on sliding at high load deforms plastically and progressive transfer of material to the counterface, and its re-depostition leads to seizure of matrix Al-7Si alloy. In case of Al-7Si alloy, the wear Kumar et al. (Ref 20) have studied the wear property of Al- 7Si alloy reinforced with 5 and 10 wt.% TiB» composite and found 36 and 66% improvement in wear properties, respec- tively, compared with the Al-7Si alloy. The wear rate reduced with increase in wt.% TiB>. Also the increase in TiB> causes
Fig. 8 SEM micrographs of wor surface of (a, b) Al-7Si alloy and (c, d) Al-7Si-10TiB» at different magnifications under a normal load of 120 N. The arrow marks show the sliding direction (Ref 20)
Fig. 8 SEM micrographs of wor surface of (a, b) Al-7Si alloy and (c, d) Al-7Si-10TiB» at different magnifications under a normal load of 120 N. The arrow marks show the sliding direction (Ref 20)
Fig. 9 SEM micrographs of wear tracks of Al 6063 alloy and Al 6063-TiB2 in situ composites at a load of 10 N and sliding velocity of 0.209 m/s (Ref 67)
Fig. 9 SEM micrographs of wear tracks of Al 6063 alloy and Al 6063-TiB2 in situ composites at a load of 10 N and sliding velocity of 0.209 m/s (Ref 67)
Fig. 10 (a) UTS and (b) yield strength for Al-TiB, in situ composites (References are shown in brackets)
Fig. 10 (a) UTS and (b) yield strength for Al-TiB, in situ composites (References are shown in brackets)
Fig. 11 SEM photomicrograph of (a) Al-5Ti-0.8C master alloy containing TiAl; and TiC particles in Al matrix, (b) Al-STi-1.2C master alloy containing only TiC particles in Al matrix and (c) XRD patterns of Al-5Ti-0.8C and Al-5Ti-1.2C master alloys and those of extracted TiC parti- cles (Ref 23)
Fig. 11 SEM photomicrograph of (a) Al-5Ti-0.8C master alloy containing TiAl; and TiC particles in Al matrix, (b) Al-STi-1.2C master alloy containing only TiC particles in Al matrix and (c) XRD patterns of Al-5Ti-0.8C and Al-5Ti-1.2C master alloys and those of extracted TiC parti- cles (Ref 23)
Fig. 12 (a) XRD pattern of Al-TiC composite and (b) optical microstructure of Al-TiC composite at low and higher magnification (Ref 78) From the theoretical calculations, one mole of K2ZrF¢ and two mole of KBF, are required to produce | mole of ZrB2 (Ref 84). Zhao et al. (Ref 40) have suggested the reactions for the formation of TiB, and ZrB, reinforcement in Al alloy using KBF,, K,ZrFs and K,TiF, salts along with the Gibbs free The improvement in the hardness is of the order of 2 and 6 for 12 and 18 vol.% TiC respectively, whereas the reduction in wear rate is in the order of 4 and 7 for 12 and 18 vol.% TiC respectively (Ref 79). Al-5 wt.% TiC composite showed 50% increase in hardness and 78% increase in 0.2% proof stress (compressive) (Ref 69). To improve the distribution of TiC in Al-TiC composite, rolling and forging were done which also improved the mechanical properties. Rolling and forging improved the yield and tensile strengths of Al-TiC composites through the strain hardening mechanism and in the case of hot rolling and for hot forging, the strengthening effect was found
Fig. 12 (a) XRD pattern of Al-TiC composite and (b) optical microstructure of Al-TiC composite at low and higher magnification (Ref 78) From the theoretical calculations, one mole of K2ZrF¢ and two mole of KBF, are required to produce | mole of ZrB2 (Ref 84). Zhao et al. (Ref 40) have suggested the reactions for the formation of TiB, and ZrB, reinforcement in Al alloy using KBF,, K,ZrFs and K,TiF, salts along with the Gibbs free The improvement in the hardness is of the order of 2 and 6 for 12 and 18 vol.% TiC respectively, whereas the reduction in wear rate is in the order of 4 and 7 for 12 and 18 vol.% TiC respectively (Ref 79). Al-5 wt.% TiC composite showed 50% increase in hardness and 78% increase in 0.2% proof stress (compressive) (Ref 69). To improve the distribution of TiC in Al-TiC composite, rolling and forging were done which also improved the mechanical properties. Rolling and forging improved the yield and tensile strengths of Al-TiC composites through the strain hardening mechanism and in the case of hot rolling and for hot forging, the strengthening effect was found
Fig. 13 SEM micrographs of the composites synthesized from Al-x wt.% (K2ZrFs-KBF4) systems. (a) x = 10, (b) x = 15, (c) x = 20 and (d) x = 25 (Ref 86)
Fig. 13 SEM micrographs of the composites synthesized from Al-x wt.% (K2ZrFs-KBF4) systems. (a) x = 10, (b) x = 15, (c) x = 20 and (d) x = 25 (Ref 86)
Fig. 14 Hardness, UTS and elongation properties of Al 6061-ZrB, composite with increase in wt.% of ZrB» (Ref 84)
Fig. 14 Hardness, UTS and elongation properties of Al 6061-ZrB, composite with increase in wt.% of ZrB» (Ref 84)
Fig. 15 Optical micrographs of refined specimens with different particle volume fractions. (a) 2024AlI alloy, (b) 2024AI1-3.1% ZrB», (c) 2024AI-5.4% ZrBo, (d) 2024Al-8.1% ZrB> (Ref 83)
Fig. 15 Optical micrographs of refined specimens with different particle volume fractions. (a) 2024AlI alloy, (b) 2024AI1-3.1% ZrB», (c) 2024AI-5.4% ZrBo, (d) 2024Al-8.1% ZrB> (Ref 83)
Fig. 16 Tensile strength, yield stress, and elongation of the 2024Al1 matrix composites reinforced by the ZrB nano-particles with different parti- cle volume fractions (Ref 84)
Fig. 16 Tensile strength, yield stress, and elongation of the 2024Al1 matrix composites reinforced by the ZrB nano-particles with different parti- cle volume fractions (Ref 84)
Fig. 17 Schematic of the setup for the AIN formation in Al melt by NH3 gas purging and model for the formation of NH3 bubble with Al melt (Ref 87, 88)
Fig. 17 Schematic of the setup for the AIN formation in Al melt by NH3 gas purging and model for the formation of NH3 bubble with Al melt (Ref 87, 88)
Fig. 18 The optical micrographs of (a) in situ Al-AIN after 2 h reaction and (b) Al-4Mg-AIN composite after 4 h reaction at gas flow rate of 0.4 lpm (Ref 90)
Fig. 18 The optical micrographs of (a) in situ Al-AIN after 2 h reaction and (b) Al-4Mg-AIN composite after 4 h reaction at gas flow rate of 0.4 lpm (Ref 90)
Fig. 19 The mechanical properties of Al-AIN/TiN composite with various reinforcement contents in three alloys prepared with 10, 20, and 30 S nitriding time (Ref 92)
Fig. 19 The mechanical properties of Al-AIN/TiN composite with various reinforcement contents in three alloys prepared with 10, 20, and 30 S nitriding time (Ref 92)
Fig. 20 (a) SEM micrograph of cast Al-Al,O3 composite showed uniform distribution of the particle and (b) XRD graph of the composi! shows the formation of Al,O3 (Ref 6)
Fig. 20 (a) SEM micrograph of cast Al-Al,O3 composite showed uniform distribution of the particle and (b) XRD graph of the composi! shows the formation of Al,O3 (Ref 6)
Fig. 22 Optical micrograph of Al-12Mg-6.9Si alloy (a) without ultrasonic injection (b) with ultrasonic injection (Ref 102)
Fig. 22 Optical micrograph of Al-12Mg-6.9Si alloy (a) without ultrasonic injection (b) with ultrasonic injection (Ref 102)
Fig. 23 Optical microstructures of in situ Al-15 wt.%Mg,Si composite with different Na additions. (a) 0 wt.%, (b) 0.05 wt.%, (c) 0.1 wt.% and (d) 0.15 wt.% (Ref 112)
Fig. 23 Optical microstructures of in situ Al-15 wt.%Mg,Si composite with different Na additions. (a) 0 wt.%, (b) 0.05 wt.%, (c) 0.1 wt.% and (d) 0.15 wt.% (Ref 112)
Fig. 24 Microstructure of permanent mold Al-15%Mg,Si composite and (b) the microstructure after modification with 0.3%Li (Ref 102)
Fig. 24 Microstructure of permanent mold Al-15%Mg,Si composite and (b) the microstructure after modification with 0.3%Li (Ref 102)
Fig. 25 (a) Hardness of Al-15%Mg,Si composite and (b) UTS and Elongation as a function of Y concentration (Ref 104) which is shown in Fig. 24. Sun et al. (Ref 116) studied the effect of 0.05% Sr, 0.20% of red phosphorous and 0.30% of aCl + 30 MgCl, + 10 KCl mixtures in Al-12Si with 5-20% Mg reinforced Mg>Si composite and observed increase in volume fraction and size of the primary Mg)Si particle. 0.4% Sb addition in Al-Si alloy reinforced with in situ Mg>Si composite refines the primary Mg,Si phase (Ref 103). Primary Mg>Si particle morphology is changed from dendritic to polygonal, and its size decreases from 47.5 to 13.0 um with the addition of Nd in Al-18 wt.% Mg,Si in situ composites. Also, the morphology of the eutectic Mg»Si phase is altered from flake-like to a thin laminar, short fibrous, and coral-like or dot-like structure (Ref 3). The effect of mechanical and wear behavior of in situ Mg>Si composites was reported by many researchers. The modifica- tion of primary and eutectic Mg>Si particle further improves the mechanical and wear properties (Ref 105-107, 109, 110, 115, 118, 120). Li addition in Al-15 wt.% Mg>Si composite reduces the size of primary Mg>Si and improved elongation in order of two and 20% improvement in UTS (Ref 119). With the effect of ultrasonic vibration in the Al-Mg>Si composite melt, the Mg>Si particle size got refined and the tensile strength was improved by 30%, from 112 to 148 MPa, which is shown in Fig. 25 (Ref 101). Ahlatci et al. (Ref 111) and Sun et al. (Ref 116) reported 1.5 times improvement in the hardness and 40% improvement in compressive strength with the addition of 20% Mg in Al- 12Si alloy (AI-5Si-45V- Mg>Si in final composition). Na addition refines the size of primary Mg>Si particles in Al- 15 wt.% Mg,Si composite and with 0.1 wt.% Na addition, 12% improvement in UTS and 38% improvement in percentage elongation obtained (Ref 112).
Fig. 25 (a) Hardness of Al-15%Mg,Si composite and (b) UTS and Elongation as a function of Y concentration (Ref 104) which is shown in Fig. 24. Sun et al. (Ref 116) studied the effect of 0.05% Sr, 0.20% of red phosphorous and 0.30% of aCl + 30 MgCl, + 10 KCl mixtures in Al-12Si with 5-20% Mg reinforced Mg>Si composite and observed increase in volume fraction and size of the primary Mg)Si particle. 0.4% Sb addition in Al-Si alloy reinforced with in situ Mg>Si composite refines the primary Mg,Si phase (Ref 103). Primary Mg>Si particle morphology is changed from dendritic to polygonal, and its size decreases from 47.5 to 13.0 um with the addition of Nd in Al-18 wt.% Mg,Si in situ composites. Also, the morphology of the eutectic Mg»Si phase is altered from flake-like to a thin laminar, short fibrous, and coral-like or dot-like structure (Ref 3). The effect of mechanical and wear behavior of in situ Mg>Si composites was reported by many researchers. The modifica- tion of primary and eutectic Mg>Si particle further improves the mechanical and wear properties (Ref 105-107, 109, 110, 115, 118, 120). Li addition in Al-15 wt.% Mg>Si composite reduces the size of primary Mg>Si and improved elongation in order of two and 20% improvement in UTS (Ref 119). With the effect of ultrasonic vibration in the Al-Mg>Si composite melt, the Mg>Si particle size got refined and the tensile strength was improved by 30%, from 112 to 148 MPa, which is shown in Fig. 25 (Ref 101). Ahlatci et al. (Ref 111) and Sun et al. (Ref 116) reported 1.5 times improvement in the hardness and 40% improvement in compressive strength with the addition of 20% Mg in Al- 12Si alloy (AI-5Si-45V- Mg>Si in final composition). Na addition refines the size of primary Mg>Si particles in Al- 15 wt.% Mg,Si composite and with 0.1 wt.% Na addition, 12% improvement in UTS and 38% improvement in percentage elongation obtained (Ref 112).
Related topics:
Aluminium Based Composite MaterialAluminium Matrix CompositesAluminium Metal Matrix Composites (Al-MMC)In Situ Metal Matrix Composites
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