Nanomaterials are now well established as a distinct class of materials. Among them, the nanoparticles of metals and alloys constitute an important subclass that has attracted wide attention from the point of view of scientific understanding and wide domain of potential applications. The present review primarily deals with alloy nanoparticles or nanoalloys containing more than one element having single or multiphase microstructure. Both free, as well as embedded alloy nanoparticles, will be considered. The physical and chemical properties of nanoalloys can be tuned by manipulating the type of metals, their compositions, and the degree of the atomic arrangement, shape, and size. These are often controlled by phase transformation. The present article reviews the recent advances in phase transformation behaviour of the alloy nanoparticles by focussing on the single and biphasic alloy of free and embedded nanoparticles; the effect of size, shape, and chemical order on the phase transformation and alloying at the nanoscale. Particular emphasis will be on melting, solidification, and order-to-disorder transformation, taking into account the extensive and detailed theoretical analysis available using thermodynamics and kinetics. Wherever needed, we shall compare free and embedded nanoparticles and invoke the results of elemental metal nanoparticles to highlight the similarities and differences. Towards the end, the unresolved issues and future directions of research on nanoalloys will be deliberated.

纳米材料现在已经确立为一类独特的材料。其中，金属和合金的纳米粒子构成了一个重要的子类，从科学认识和潜在应用的广泛领域来看，受到了广泛的关注。本综述主要涉及合金纳米颗粒或含有一种以上具有单相或多相微观结构元素的纳米合金。将考虑免费和嵌入的合金纳米粒子。纳米合金的物理和化学性质可以通过操纵金属的类型、它们的成分以及原子排列的程度、形状和尺寸来调节。这些通常由相变控制。本文通过关注游离和嵌入纳米粒子的单相和双相合金，回顾了合金纳米粒子相变行为的最新进展；尺寸、形状和化学顺序对纳米级相变和合金化的影响。将特别强调熔化、凝固和有序到无序的转变，同时考虑到使用热力学和动力学的广泛和详细的理论分析。在需要时，我们将比较游离和嵌入的纳米粒子，并调用元素金属纳米粒子的结果来突出异同。最后，将讨论纳米合金的未解决问题和未来研究方向。尺寸、形状和化学顺序对纳米级相变和合金化的影响。将特别强调熔化、凝固和有序到无序的转变，同时考虑到使用热力学和动力学的广泛和详细的理论分析。在需要时，我们将比较游离和嵌入的纳米粒子，并调用元素金属纳米粒子的结果来突出异同。最后，将讨论纳米合金的未解决问题和未来研究方向。尺寸、形状和化学顺序对纳米级相变和合金化的影响。将特别强调熔化、凝固和有序到无序的转变，同时考虑到使用热力学和动力学的广泛和详细的理论分析。在需要时，我们将比较游离和嵌入的纳米粒子，并调用元素金属纳米粒子的结果来突出异同。最后，将讨论纳米合金的未解决问题和未来研究方向。考虑到使用热力学和动力学的广泛和详细的理论分析。在需要时，我们将比较游离和嵌入的纳米粒子，并调用元素金属纳米粒子的结果来突出异同。最后，将讨论纳米合金的未解决问题和未来研究方向。考虑到使用热力学和动力学的广泛和详细的理论分析。在需要时，我们将比较游离和嵌入的纳米粒子，并调用元素金属纳米粒子的结果来突出异同。最后，将讨论纳米合金的未解决问题和未来研究方向。