Chang Liu

Xi'an Jiaotong University | XJTU · State Key Laboratory for Mechanical Behavior of Materials

Grain boundary hardening and precipitation hardening are important mechanisms for enhancing the strength of metals. Here, we show that these two effects can be amplified simultaneously in nanocrystalline compositionally complex alloys (CCAs), leading to near-theoretical strength and large deformability. We develop a model nanograined (TiZrNbHf)98Ni...

Oxygen interstitial solutes have traditionally been thought to occupy only octahedral interstices in body-centered cubic (bcc) metals. However, there is ongoing debate about the competition between tetrahedral and octahedral interstitial sites for oxygen solutes in multi-principal element alloys, especially following recent experimental evidence ob...

The transformation induced plasticity phenomenon occurs when one phase transforms to another one during plastic deformation, which is usually diffusionless. Here we present elemental partitioning-mediated crystalline-to-amorphous phase transformation during quasi-static plastic deformation, in an alloy in form of a Cr-Ni-Co (crystalline)/Zr-Ti-Nb-H...

Metallurgists have long been accustomed to a trade-off between yield strength and tensile ductility. Extending previously known strain-hardening mechanisms, the emerging multi-principal-element alloys (MPEAs) offer additional help in promoting the strength-ductility synergy, towards gigapascal yield strength simultaneously with pure-metal-like tens...

A novel multi-principal element alloy was developed by integrating oxygen incorporation with dual-phase supra-nanostructuring to boost catalytic efficacy due to its abundant, unique next-nearest oxygen-coordinated active sites in interfaces.

Thermal stability determines a material's ability to maintain its performance at desired service temperatures. This is especially important for aluminum (Al) alloys, which are widely used in the commercial sector. Herein, an ultra‐strong and heat‐resistant Al‐Cu composite is fabricated with a structure of nano‐AlN and submicron‐Al2O3 particles unif...

To alleviate the mechanical instability of major shear bands in metallic glasses at room temperature, topologically heterogeneous structures were introduced to encourage the multiplication of mild shear bands. Different from the former attention on topological structures, here we present a compositional design approach to build nanoscale chemical h...

Interstitial solutes, such as carbon in steels, are effective solid‐solution hardening agents. These alloying elements are believed to occupy the octahedral interstices in body‐centered‐cubic (bcc) metals. Using deep‐sub‐angstrom resolution electron ptychography, here we provide the first experimental evidence to directly observe individual oxygen...

Platinum-based catalysts are widely used in hydrogen evolution reactions; however, their applications are restricted because of the cost-efficiency trade-off. Here, we present a thermodynamics-based design strategy for synthesizing an Al 73 Mn 7 Ru 20 (atomic %) metal catalyst via combinatorial magnetron co-sputtering. The new electrocatalyst is co...

We design and investigate a ferritic multicomponent alloy with high electrical resistivity, low temperature coefficient of resistivity (TCR) in a wide-temperature range, high strength, and moderate deformability, aiming to overcome the bottlenecks limiting the development of cost-efficient high-quality resistors. The developed bulk alloy with nomin...

Interstitials, e.g., C, N, and O, are attractive alloying elements as small atoms on interstitial sites create strong lattice distortions and hence substantially strengthen metals. However, brittle ceramics such as oxides and carbides usually form, instead of solid solutions, when the interstitial content exceeds a critical yet low value (e.g., 2 a...

The design of high performance structural materials is always pursuing combinations of excellent yet often mutually exclusive properties such as mechanical strength, ductility and thermal stability. Although crystal-glass composite alloys provide better ductility compared to fully amorphous alloys, their thermal stability is poor, due to heterogene...

Wear-related energy and material loss cost over 2500 Billion Euro per year. Traditional wisdom suggests that high-strength materials reveal low wear rates, yet, their plastic deformation mechanisms also influence their wear performance. High strength and homogeneous deformation behavior, which allow accommodating plastic strain without cracking or...

The mechanical behavior and deformation mechanisms of a body-centered cubic (BCC) Ti29Zr24Nb23Hf24 (at.%) high entropy alloy (HEA) was investigated in temperatures and strain rates from 700 to 1100 °C and 10⁻³ to 10 s⁻¹, respectively. The HEA exhibits a substantial increase in yield stress with increasing strain rate. The strain rate sensitivity (S...

Dual-phase metallic glasses (DP-MGs), a special member of the MGs family, often reveal unusual strength and ductility, yet, their corrosion behaviors are not understood. Here, we developed a nanostructured Mg57Zn36Ca7 (at.%) DP-MG and uncovered its corrosion mechanism in simulated body fluid (SBF) at the near-atomic scale utilizing transmission ele...

The corrosion resistance of the equiatomic CoCrNi medium-entropy alloy (MEA) and its 0.5 atomic % nitrogen alloyed variant in 0.1 M H2SO4 solution was investigated and compared with that of the 316L stainless steel as a reference material. All of the investigated materials showed single-phase face centered cubic (FCC) microstructures, and nitrogen...

We investigate the strain-rate-dependent mechanical behavior and deformation mechanisms of a refractory high entropy alloy, Ti29Zr24Nb23Hf24 (at.%), with a single-phase body-centered cubic (BCC) structure. High-temperature compression tests were conducted at temperatures from 700 to 1100{\deg}C at strain rates ranging from 10-3 to 10 s-1. A sudden...

Since its first emergence in 2004, the high-entropy alloy (HEA) concept has aimed at stabilizing single-or dual-phase multi-element solid solutions through high mixing entropy. Here, this strategy is changed and renders such massive solid solutions metastable, to trigger spinodal decomposition for improving the alloys' magnetic properties. The moti...

We report a room temperature ultrahigh yield strength (3.0 GPa in compression) and large deformability (above 50% compressive strain) of a magnesium-based nano-dual-phase glass-crystal alloy in sub-micro size, compared with brittle nature of its own structural units. Transmission electron microscope investigation, molecular dynamic simulation and c...

Magnesium (Mg) alloys are good candidates for applications with requirement of energy saving, taking advantage of their low density. However, the fewer slip systems of the hexagonal-close-packed (hcp) structure restrict ductility of Mg alloys. Here, a hybrid nanostructure concept is presented by combining nano-dual-phase metallic glass (NDP-MG) and...

High‐entropy alloys (HEAs) and metallic glasses (MGs) are two material classes based on the massive mixing of multiple‐principal elements. HEAs are single or multiphase crystalline solid solutions with high ductility. MGs with amorphous structure have superior strength but usually poor ductility. Here, the stacking fault energy in the high‐entropy...

We report an excellent tensile property of the Mg-based nano-dual-phase glass-crystal alloy in sub-micro size. It shows room temperature large ductility (>50% true strain, resulted from the localized necking deformation) with ultrahigh tensile strength (2.4 GPa), compared with 1.4 GPa strength and limited ductility of its metallic glass counterpart...

Selective oxidation of Fe2MnxSi alloys with various Si contents annealed in a gas mixture of H2/H2O (p(O2) = 6.5×10⁻²⁵ bar at 700 °C) for 2 h was investigated. The oxidation kinetics of all the alloys followed linear growth, indicating that most likely oxygen uptake was the rate-determining step. The addition of Si into Fe2Mn eliminated the formati...

High strength and high ductility are often mutually exclusive properties for structural metallic materials. This is particularly important for aluminum (Al)-based alloys which are widely commercially employed. Here, we introduce a hierarchical nanostructured Al alloy with a structure of Al nanograins surrounded by nano-sized metallic glass (MG) she...

AISI 301 stainless steel (SS) is known for its high strength and hardness but tends to be less corrosion resistant for many applications. Several attempts have been made in the past to investigate its corrosion behavior by different methods. However, current knowledge is insufficient on its corrosion resistance when subjected to surface treatment....

A magnesium-based ‘supra-nanometre-sized dual-phase glass-crystal’ (SNDP-GC) coating had been fabricated on AZ31 alloy by magnetron sputtering. Surface mechanical attrition treatment (SMAT) was also introduced to form a gradient structure in order to reduce the hardness mismatch between Mg-based SNDP-GC coating and substrate. Microstructure, mechan...

Ceramics are widely used as engineering materials due to their high strength; however, their lack of plasticity is a major drawback. We report that dual-phase amorphous carbon (a-C) reveals high yield strength of ∼E/11 (E is elastic modulus, and E/10 is theoretical limit for ideal material) and large plasticity of ∼70% at room temperature in uniaxi...

The CoCrMo alloy was ion implanted by carbon with implantation fluences from 1.0 × 10¹⁷ to 9.0 × 10¹⁷ ions/cm². The nanostructure and phase transformation in CoCrMo alloy due to carbon ion implantation were investigated using high-resolution transmission electron microscopy (HRTEM). The tribocorrosion behavior was investigated by using a ball-on-di...