Chezheng Cao

University of California, Los Angeles | UCLA · Department of Materials Science and Engineering

Aluminum is one of the most abundant lightweight metals on Earth with broad practical applications, such as in electrical wires. Although traditional aluminum manufacturing by alloying, deformation and thermomechanical means addresses the balance between high strength and high conductivity, adding metallic ceramic nanoparticles into the aluminum ma...

For many alloys, bulky and brittle intermetallic phases are detrimental to their properties, and the refinement of those phases is considered a long-time challenge. Here, we show that nanoparticles (NPs) can modify and refine such intermetallics to the ultrafine/nanoscale during solidification. Cu-ZrCuSi pseudo-binary alloy was nano-treated by appr...

Bimodal grain structure has been demonstrated effective to overcome the strength-ductility tradeoff in nanostructured materials. Here we report a new and scalable method to fabricate bimodal grained metals, i.e., casting followed by regular hot rolling, when the metals are loaded with nanoparticles. The as-solidified copper (Cu) containing tungsten...

Ultra-long metal nanowires and their facile fabrication have been long sought after as they promise to offer substantial improvements of performance in numerous applications. However, ultra-long metal ultrafine/nanowires are beyond the capability of current manufacturing techniques, which impose limitations on their size and aspect ratio. Here we s...

Ultrafine-grained (UFG)/nanocrystalline materials possess novel properties. Refining as-solidified grains of metals to the ultrafine and even nanometer scale by nanoparticles via slow cooling has been recently discovered. Here, we report that microparticles (CrB and CrB2) with surface nanofeatures can also enable ultrafine/nano grains via slow cool...

There is a significant demand for Cu-based materials with high strength and high electrical conductivity for a wide range of applications. However, the long-standing trade-off between mechanical properties and electrical conductivity often inhibits the development of such high-performance Cu materials. Cu-based metal matrix nanocomposites (MMNCs) a...

Silica gels offer excellent wear resistance, high chemical stability, good insulation, and light transmittance, are therefore promising to engineer 2D sensing films. However, their practical applications are greatly hampered by their poor structural stability, low sensitivity, reliability, and repeatability. Incorporation of nanoelements into glass...

Chromium borides (CrBx) have been considered as promising strengthening phases for copper (Cu). However, traditional manufacturing methods such as powder metallurgy greatly restrict the sample size and part complexity. Here, we report that bulk Cu containing high volume percentages of uniformly distributed CrBx were fabricated by casting via in-sit...

While laser-printed metals do not tend to match the mechanical properties and thermal stability of conventionally-processed metals, incorporating and dispersing nanoparticles in them should enhance their performance. However, this remains difficult to do during laser additive manufacturing. Here, we show that aluminum reinforced by nanoparticles ca...

Cooling, nucleation, and phase growth are ubiquitous processes in nature. Effective control of nucleation and phase growth is of significance to yield refined microstructures with enhanced performance for materials. Recent studies reveal that ultrafine grained (UFG)/nanocrystalline metals exhibit extraordinary properties. However, conventional micr...

The microstructure and mechanical responses of a pseudo-dispersed Al-TiC nanocomposite were thoroughly studied using micropillar compression and high-resolution transmission electron microscopy (HRTEM). The microstructure of the Al-7 vol pct TiC nanocomposite comprised the α-Al matrix, DO22-Al3Ti platelet and Al4C3, along with TiC domains in which...

Metal matrix nanocomposites (MMNCs) with nanoparticles in a metal matrix are important for widespread applications. Smaller nanoparticles are preferred for a better strengthening effect. However, it is extremely difficult to control the size of nanoparticles in MMNCs through a solidification process. In this study, a novel in-situ molten salt react...

Nano-treating is a novel concept wherein a low percentage of nanoparticles is used for microstructural control and property tuning in metals and alloys. The nano-treating of AA7075 was investigated to control its microstructure and improve its structural stability for high performance. After treatment with TiC nanoparticles, the grains were signifi...

Glassy materials can be broadly defined as any amorphous solid, which are important in nature and have significant societal value for their applications in daily life and industry. Although many methods have been applied, the fracture toughness of traditional glasses is still very low due to intrinsic brittleness, significantly limiting their use f...

High loading of WC nanoparticles was successfully incorporated into the alloy system Cu-40 wt% Zn by molten salt stirring method. Given the energy balance of thermal energy, van der Waals interaction and inter-particle barrier, the expected pseudo-dispersion of WC was stable. In order to evaluate the materials functional applicability, the mechanic...

Nanoparticles can be added to metals to tune their properties for numerous applications. Recently extensive research has been conducted to measure the mechanical properties of nanoparticle reinforced metals. However, few theories exist to understand how nanoparticles interact with metals to affect their electrical performance, partly due to the dif...

Copper (Cu) has high electrical conductivity and is widely used for many industrial applications. However, pure Cu is very soft and improving the mechanical properties of Cu comes at the great expense of electrical and thermal conductivity. In this work, high-performance Cu with superior mechanical properties and reasonable electrical/thermal condu...

Graphene liquid cells (GLCs) have attracted increasing attention in nanoscience fields, which significantly broaden strategies of studying in-situ activities of nanoparticles in the liquid phase. Here, we report a simplified approach for the fabrication of GLCs using ultrasonication assistance. We show morphologies and performance of fabricated GLC...

Lightweight materials are of paramount importance to reduce energy consumption and emissions in today’s society. For materials to qualify for widespread use in lightweight structural assembly, they must be weldable or joinable, which has been a long-standing issue for high strength aluminum alloys, such as 7075 (AA7075) due to their hot crack susce...

Nanoscale titanium diborides (TiB2) can be utilized in numerous applications ranging from wear resistant coating to conducting polymers. However, a surface-clean TiB2 nanoparticles with less than 10 nm in size is not currently available in either commercial or literature. Here we report a novel yet scalable synthesis of ultra-fine and uniform size...

Titanium carbide (TiC) nanoparticles have great potential for strengthening metals as TiC has high hardness, high Young's modulus, good conductivity and excellent wear resistance. To enable effective Orowan strengthening effect, smaller TiC nanoparticles (e.g. < 10 nm) are highly preferred. However, small TiC nanoparticles (< 10 nm) are not availab...

Aluminum matrix nanocomposite (AMNC) materials are of great interests for various structural and functional applications for automotive, aerospace, and military. In this study pure aluminum (Al) with one and two volume percent (vol.%) of titanium diboride (TiB2) nanoparticles were produced via flux-assisted liquid state processing. Adding flux duri...

There is a longstanding challenge to disperse metal nanoparticles uniformly in bulk polymers for widespread applications. Conventional scale-down techniques often are only able to shrink larger elements (such as microparticles and microfibers) into micro/nano-elements (i.e. nanoparticles and nanofibers) without much altering their relative spatial...

Effective control of melting and solidification behaviours of materials is significant for numerous applications. It has been a long-standing challenge to increase the melted zone (MZ) depth while shrinking the heat-affected zone (HAZ) size during local melting and solidification of materials. In this paper, nanoparticle-induced unusual melting and...

Supplementary Figures, Supplementary Table, Supplementary Note and Supplementary References.

Thermal fiber drawing process has emerged as a promising nanomanufacturing process to generate high-throughput, well aligned, and indefinitely long micro/nano structures. However, scalable fabrication of metal polymer nanocomposite is still a challenge since it is still very difficult to control metal core geometry at nanoscale due to the low visco...

It is of great scientific and technical interests to conduct fundamental studies on the laser interactions with nanoparticles-reinforced metals. This part of the study presents the effects of nanoparticles on surface tension and viscosity, thus the heat transfer and fluid flow, and eventually the laser melting process. In order to determine the sur...

It is of tremendous interests to apply laser to process nanoparticles-reinforced metals for widespread applications. However, little fundamental understanding has been obtained on the underlining physics of laser interactions with nanoparticles-reinforced metals. In this paper, fundamental study was carried out to understand the effects of nanopart...

Mg-based metal matrix nanocomposites (MMNCs) are expected to provide significant enhancement of properties by introducing thermally stable ceramic nanoparticles into the metal matrix. However, it is extremely difficult to achieve a uniform distribution of nanoparticles in the magnesium matrix for the predicted significant property enhancement. In t...

Mg-based metal matrix nanocomposites (MMNCs) are expected to provide significant enhancement of properties by introducing thermally stable ceramic nanoparticles into the metal matrix. However, it is extremely difficult to achieve a uniform distribution of nanoparticles in the magnesium matrix for the predicted significant property enhancement. In t...

The novel properties of diamond/Cu composites such as low thermal expansion coefficient and high thermal conductivity have rendered the composites a valuable packaging material. The reactive brazing of diamond/Cu composites and alumina was performed using the 97%(72Ag-28Cu)-3%Ti alloy. The reactive brazing alloy displays good wettability with alumi...

Reactive brazing of diamond/Cu composites to alumina by 97(72Ag-28Cu)-3Ti alloy was performed. The influence of the main brazing parameters, such as peak heating temperature and holding time, on microstructure and properties of the brazing joint was investigated. The results show that Ti element tends to concentrate at the surface of diamond partic...