Synergistic Effect of La and TiB2 Particles on Grain Refinement in Aluminum Alloy

Synergistic effect of TiB2 (in form of Al-5Ti-1B) and La on grain refining results in Al-2Cu alloy was investigated. α-Al grains are significantly refined by Al-5Ti-1B. When trace La is added to the melt, further refinement is exhibited. Average grain size and nucleation undercooling of α-Al reduce first and then almost remain unchanged with La addition. Satisfactory grain refining result achieves when La addition level reaches 600 ppm. When more than 600 ppm La is added to the melt, La-rich particles form and the effect of solute La left in matrix on the microstructure almost no longer changes. Theoretical calculation results demonstrate that solute La segregates to Al melt/TiB2 particles interface along with Ti and Cu prior to α-Al nucleation and the synergistic effect of La and TiB2 particles on grain refinement mainly attributes to the enhancement in the potency of TiB2 particles to heterogeneously nucleate α-Al by trace La addition.

New Paradigm On The Mechanical Properties of In-Situ Formed By Al/TiB2 and Al/TiB2/Cu MMCs

In the current study, in-situ formed Al/6wt. % TiB2 and Al/6wt. % TiB2/4wt. % Cu Metal Matrix were investigated. Composites were made using the sir casting method, and both composites were compared. The composite is synthesized by combining two precursor salts, Potassium Hexa Fluro Titanate (KBF4) and potassium tetrafluoroborate (K2TiF6), with stoichiometric compositions corresponding to 6 percent by weight of TiB2 particles, with A356 aluminium melt at 820° C, speed 300 rpm, and holding time 30 minutes. Following that, 4wt. % Cu powder was added to the composite melt, which was then poured into the permanent mould. Mechanical properties tests such as tensile strength, hardness, and fracture toughness were carried out in accordance with ASTM guidelines. The mechanical properties of the in-situ formed Al/6wt. % TiB2/4wt. % Cu composite outperform those of the Al/6wt.% TiB2 composite and base metal. Optical micrograph and XRD analysis both confirm the presence of TiB2 and Cu particles.

Role of Reinforcement Particle Size and Its Dispersion on Room Temperature Dry Sliding Wear of AA7075/TiB2 Composites

Aluminum alloy based metal matrix composites (AMCs) are widely accepted material in the aerospace, automotive, military, and defence applications due to lightweight and high strength. For tribological applications, high-performance wear-resistant materials like AMCs are the candidate materials. In this investigation, AA7075 based composites with different size TiB2 particles were fabricated using in-situ and ultrasound casting techniques (UST). The AMCs were tested using pin-on-disc tribo tester and the effects of different sized TiB2 particles on wear resistance of AA7075/TiB2 composites have been investigated. The wear resistance of AA7075/TiB2 composite fabricated using UST is found to significantly improve when compared to base alloy and also in-situ composite due to refinement in the particle size, reduced the agglomeration, and improved the distribution of TiB2 particles. The test results also revealed the existence of a mixture of mechanically mixed Al–Zn–Fe intermetallic alloy and oxides of these elements.

Analyzing the Cooling Rate and Its Effect on Distribution of Pattern and Size of the Titanium Diboride Particles Formed

In this work, we synthesize Al/TiB2 metal matrix composites (MMC) based on the effect of cooling rate in the melt while pouring into the permanent mold condition. The objective of this paper is to achieve the desired distribution pattern and increased TiB2 particles’ size in the Al/TiB2 MMC ingot. Two halide salts, viz., potassium hexafluorotitanate (K2TiF6) and potassium tetrafluoroborate (KBF4), are procured and measured. The two salts were mixed with the aluminium melt in the crucible, and it is stirred manually with help of a graphite rod. Because of the exothermic reaction, the melt reacts very quickly and that is what dropped the salts slowly. The salt particles were synthesized because of the exothermic reaction, and it will allow the particles to grow. The size and distribution of particles differ at different place in the MMC. An FEA tool ProCAST was used to analyze the cooling rate of the melt, and SEM is used to study the microstructure of the ingot at different places. The microstructures helped to identify the size of reinforcement in the MMC. The TiB2 particles are distributed more at this location at 810°C, and the TiB2 particles formed various clusters in this zone as 70%–80%. Also, the tribological characteristics are analyzed with the help of the results.

The effect of V on the morphology of TiB2 particles in as-cast aluminum composites

This study presents the modification effect of trace vanadium on the in-situ formed TiB2 particles in as-cast aluminum composites. With 0.2 wt.% V addition the morphology of TiB2 was modified from hexagonal platelet or irregular feather-like shape to hexagonal prism or rectangular prism with parallel growth steps along the c-axis. Meanwhile, V rich cores were detected in the center of TiB2 and the exposure of the high-index crystal plane (1101)TiB2 was detected in Al-0.2 wt.%V. Statistical analysis of the particle size and aspect distribution both in commercial Al and Al-0.2 wt.%V was conducted. The elemental distribution and scanning electron microscopy investigation revealed that VB2 may serve as the 2D-nucleus of TiB2 particles. The growth mechanism of TiB2 under the influence of V was explored.

Trace Scandium addition on the strength and thermal stability of TiB2 particles reinforced Al-4.5 Cu composites

Strategies employed for developing ultrahigh strength and scalable ductile particles reinforced aluminium-copper matrix composites (AMCs) are highly desirable and grandly challenging. In the present paper, the Scandium (Sc) micro-alloying TiB2 particles reinforced Al-4.5 Cu composites were successfully fabricated by the optimized salt-metal reaction method. The observed microstructures displayed that Sc addition could remarkably ameliorate the dispersion of TiB2 particles, enlarge equiaxed α-Al grain zone and refine the grains on the basis of TiB2 heterogeneous nucleation. In particular, for the 0.4 wt.% Sc microalloyed 5%TiB2/Al-4.5Cu composites, more than a 20 %, 87 %, and 118 % increase in the ultimate tensile strength (UTS), fracture strain elongation (%) and microhardness (HV), respectively were found with respect to the 3 %TiB2/Al-4.5Cu composites at room temperature (298K). The improved mechanical properties of strength-ductility synergy were mainly thanks to the homogeneous distribution of TiB2 particles and modification of Al2Cu phase. Moreover, proper Sc also enhanced the elevated-temperature mechanical properties of the composites with the aid of the accelerated precipitation of θ′ phase and much lower coarsens rate.